Inclusion Criteria:
Participants are eligible for the study only if all of the following inclusion criteria are met:
1. Aged ≥ 6 to \<16 years at the time of signing the ICF (age \<16 years after 12-week treatment), including adolescents aged ≥ 12 to\<16 years at the time of signing the ICF (age \<16 years after 12-week treatment), and children aged ≥ 6 to\<12 years at the time of signing the ICF;
2. Male or female;
3. Participants diagnosed with ASD according to the ASD diagnostic criteria in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and confirmed by the Schedule for Affective Disorders and Schizophrenia for School Aged Children Present and Lifetime version (K-SADS-PL), DSM-5 ASD module;
4. Child Autism Rating Scale 2-ST (CARS 2-ST) raw score ≥36;
5. CGI-S score ≥4;
6. Participants and their legal guardians understand and are willing to participate in this trial, with ICF signed by the legal guardian and participants aged ≥ 8 years; for participants who, at the discretion of the investigator, have cognitive deficits that prevent them from signing the ICF, their legal guardians sign the ICF on behalf of them;
7. Females of childbearing potential (as defined in Appendix 15.1) agree to remain abstinent or use a reliable method of contraception for the duration of the trial and until 3 months after the last dose of the investigational product.
Exclusion Criteria:
Any participant who meets any of the following criteria will be excluded:
1. Weight \<20.0 kg or \>70.0 kg, or BMI ≥35.0 kg/m\^2;
2. Pregnant or lactating women;
3. Presence of a serious mental disorder as assessed by the investigator, e.g., schizophrenia, bipolar disorder, depressive disorder, etc.; the presence of significant anxiety, tension, agitation, fear, depression, or the presence of suicidal risk, significant risk of self-injury, impulsivity, aggression, or behaviors based on the medical history and the routine mental status examination;
4. History of epileptic seizures within 3 months prior to screening, or presence of a history of severe physical or neurological disease, history of severe head trauma;
5. Participants with a history or symptoms of other mental illness that, at the discretion of the investigator, may affect the results of the study;
6. Participants with a history of any unstable physical or neurological condition or currently suffering from a physical or neurological condition that, at the discretion of the investigator, may put them at risk of a significant adverse event or interfere with the assessment of safety and efficacy during the course of the trial;
7. Pre-existing educational training and/or behavioral treatments fail to be stabilized prior to screening and consistent throughout the trial;
8. Participants who are unable to discontinue or may use other treatments during the screening period and throughout the trial due to their condition, including: antipsychotic medications (except those that may be used in combination during the trial as specified in the protocol), medications that may have a therapeutic effect on ASD, nootropic drugs, medications for ADHD, intestinal flora modification, and other intestinal flora modification supplementation alternatives;
9. Participants who have used treatment modalities such as transcranial magnetic stimulation therapy, direct current stimulation therapy, electroencephalographic biofeedback therapy, auditory integration training, executive function training, acupuncture therapy, etc., within 2 months prior to randomization, or may use such treatments during the treatment period;
10. 12-ECG and laboratory results as outlined below: (1)QTc is outside the normal range of the site; (2)Platelets are below the lower limit of normal for the site; (3)Haemoglobin is below the lower limit of normal for the site; (4)Neutrophil count is below the lower limit of normal for the site; (5)ALT or AST ≥ 2 × upper limit of normal, or total bilirubin \> upper limit of normal for the site; (6)Urea nitrogen or creatinine is above the upper limit of normal for the site; (7)Any other abnormal laboratory, vital sign, or 12-ECG findings that, at the discretion of the investigator, are abnormal and clinically significant and will affect the safety of the participant or the interpretation of the study results;
11. Participation in any clinical trial of a drug or non-drug intervention within the last 1 month;
12. Concomitant medications/therapies that are prohibited in the protocol may be required during the trial;
13. Participants expected to undergo elective surgery during the trial;
14. Participants whose parents/guardians are unable to understand and/or complete the scale assessments in this trial.
15. Hypersensitivity to edaravone and excipients (Soluplus, sodium bisulphite, microcrystalline cellulose, magnesium stearate, polyvinylpolypyrrolidone) in TTYP01 tablets;
16. Participants who are judged by the investigator to be ineligible for other reasons.
