Inclusion Criteria:
* DCM≥1year;
* NYHA II-IV;
* LVEF ≤35%；
* Received maximally tolerated guideline-directed medical therapy (GDMT) for at least 3 months before enrollment with persistent heart failure; or unable to tolerate standardized pharmacotherapy recommended by guidelines (according to clinical data), but in which investigators assessed participants who could benefit from the study drug; or hospitalized for heart failure more than 2 times within 1 year and requiring intravenous diuretic therapy, while the condition is stable for more than 2 weeks;
* Have the ability to understand and voluntarily sign informed consent before the trial, and be able to complete the study in accordance with the requirements of the trial protocol;
* Male or female: (1) male subjects must agree to use contraception for at least 6 months after treatment visit; (2) the female subjects were not pregnant or breastfeeding; (3) Females of childbearing potential agree to comply with contraceptive guidance for at least 6 months after administration (see Appendix 1)
Exclusion Criteria:
* Patients with heart failure caused by heart diseases other than dilated cardiomyopathy (including but not limited to severe valvular heart disease, hyperthyroidism, congenital heart disease, acute viral myocarditis, acute coronary syndrome, hypertrophic obstructive cardiomyopathy, pericardial disease, myocardial amyloidosis, infiltrative cardiomyopathy, uncorrected thyroid disease, or left ventricular aneurysm).
* Coronary angiography has a degree of narrowing of the left main coronary artery (LM), left anterior descending branch (LAD), left circumflex branch (LCX) or right coronary artery (RCA) \> 50%.
* Uncontrolled arrhythmias that the investigator believes would affect this trial.
* Acute myocardial infarction within 6 months before screening
* Previous presence of subjects with immunological abnormalities that the investigators believe could affect this trial (including but not limited to congenital immunodeficiency, lupus erythematosus, primary vasculitis, systemic sclerosis, antiphospholipid syndrome, autoimmune liver disease, autoimmune thyroiditis).
* Those who have a history of tumor for less than 5 years or currently have a tumor, or those who have precancerous lesions confirmed by pathological examination (including but not limited to breast ductal carcinoma in situ, cervical dysplasia, etc.)
* Known progress liver disease (active hepatitis A, chronic hepatitis B or C virus infection, non-cardiogenic cirrhosis, etc.)
* Acute infection developed within 2 weeks prior to screening requiring intravenous antibiotic therapy, or current infection requiring anti-infective therapy.
* Those who have a history of disseminated herpes simplex infection or recurrent (\> 1 times) or disseminated herpes zoster.
* Percutaneous coronary intervention (PCI), coronary bypass grafting (CABG), Implantable Cardioverter Defibrillator (ICD)/permanent pacemaker/Cardiac resynchronisation therapy (CRT) implantation, radiofrequency ablation, ventricular volume reduction, valve repair or plasty, intra-aortic balloon counterpulsation, passive restraint devices (e.g., CorCap™ cardiac support devices), cardiac assist device implantation, heart transplantation, or other cardiac surgery may be received within 3 months prior to screening or within 3 months after administration.
* Those who donated ≥ 400 mL of blood within 4 weeks prior to screening, or who had significant blood loss equivalent to at least 400 mL, or who received blood transfusions within 8 weeks.
* Subjects with contraindications for coronary angiography
* Contraindications for Magnetic Resonance Imaging (MRI) detection, including but not limited to: pacemaker, defibrillator, artificial heart valve, metal clip after aneurysm surgery, drug perfusion device implanted in the body, any electronic device implanted in the body (neurostimulator, bone growth stimulator), intravascular embolization steel ring, filter, ECG recording monitor, shrapnel or iron sand in the body, fixed steel plate and nails after fracture surgery, cochlear implant, intraocular metal foreign body, etc.; Claustrophobia, etc.
* Those who have a history of substance abuse within the past five years or have used drugs in the 3 months prior to the test.
* Are participating in other clinical trials, or have been completed less than 3 months after the end of other clinical trials.
* Abnormal liver function: ALT or AST \> 3 times the upper limit of normal value (ULN).
* Abnormal renal function: glomerular filtration rate \< 30 mL/min or dialysis-dependent.
* Hematologic disorders: thrombocytopenia is defined as \<50,000 platelets/μL within 30 days prior to screening; Anaemia is defined as haemoglobin \<10 g/dL within 30 days prior to screening or dependence on blood transfusion; Neutropenia is defined as an absolute neutrophil value \< 1500 mm\^3 within 30 days prior to screening.
* Acquired immunodeficiency syndrome (AIDS) or human immunodeficiency virus (HIV) positive, or previously diagnosed immunodeficiency with an absolute neutrophil count \< 1000 cells/mm\^3.
* Those who are positive for treponema pallidum antibodies and positive for rapid plasma reagin test (RPR).
* AAV9 neutralizing antibody titer \> 1:50
* Subjects with a history of active tuberculosis or active or inactive TB infection at screening.
* 4 weeks prior to screening, or those who plan to receive a live (attenuated) vaccine during the trial.
* Those who smoked more than 20 cigarettes per day or habitually used nicotine-containing products in the 3 months prior to screening, drank more than 14 units of alcohol per week (1 unit of alcohol = 360mL of beer or 45mL of spirits or 150mL of wine with 40% alcohol content) or took alcohol-containing products 2 days before administration.
* The investigators believe that there are other conditions that would have an impact on intolerance to this treatment or endpoint evaluation.
