There is ambiguity and uncertainty in the method of determining the invalidity of a contract by distinguishing between validity and administrative mandatory provisions.Article 16 of the Interpretation on the General Principles of Contracts in the Civil Code adopts in essence the standard for determining the validity of a contract based on the normative purpose.This standard reflects the legitimacy of the judge's intervention in the contractual relationship in specific cases,demonstrates the protection of the public interest,and is in line with the development trend of contract law in comparative law.However,the article is incomplete and imperfect.To determine the invalidity of a contract based on the normative purpose,it is necessary to first explore whether the normative purpose of the mandatory provisions involves public interest and its type.Secondly,whether the normative purpose is aimed at the content of the contract should be determined.Finally,whether the administrative and criminal liabilities can achieve the normative purpose should be examined.The determination of invalidity of a contract based on the normative purpose shall be limited by the principle of proportionality.The contract shall not be identified as invalidity when the impact of the performance of the contract on the social public interest is significantly slight,and the determination that the contract is valid will not affect the realization of the normative purpose.