You can report to the Human Resources and Social Security Bureau or to the public security organ.

fraudulent use of other people's medical insurance cards for reimbursement is a criminal act of concealing the truth, fabricating facts and defrauding medical insurance funds. Any citizen can report to the Human Resources and Social Security Bureau or directly to the public security organ. The People's Social Security Bureau and the public security organ shall file a case for investigation.

Social Insurance Law

Article 88 Where social insurance benefits are defrauded by fraud, forgery of certification materials or other means, the social insurance administrative department shall order the social insurance benefits defrauded to be returned and impose a fine of not less than two times but not more than five times the amount defrauded.

article 94 anyone who violates the provisions of this law and constitutes a crime shall be investigated for criminal responsibility according to law.

Article 266 of the Criminal Law of the People's Republic of China

Whoever defrauds public or private property in a relatively large amount shall be sentenced to fixed-term imprisonment of not more than three years, criminal detention or public surveillance, and shall also, or shall only, be fined; If the amount is huge or there are other serious circumstances, he shall be sentenced to fixed-term imprisonment of not less than three years but not more than ten years and shall also be fined; If the amount is especially huge or there are other especially serious circumstances, he shall be sentenced to fixed-term imprisonment of not less than 1 years or life imprisonment, and shall also be fined or confiscated. Where there are other provisions in this Law, such provisions shall prevail.

the Supreme People's Court and the Supreme People's Procuratorate

Interpretation on Several Issues Concerning the Specific Application of Laws in Handling Criminal Cases of Fraud

Fa Shi [211] No.7

Article 1 Whoever cheats public or private property with a value of 3, to 1, yuan or more, 3, to 1, yuan or more, or 5, yuan or more shall be deemed as "a large amount" or "a huge amount" as stipulated in Article 266 of the Criminal Law respectively.

Further reading: How to buy insurance, which is better, and teach you how to avoid these "pits" of insurance.