Regardless of how the title might best be translated, a Google search shows that the translation "Economic Contract Law of the People's Republic of China" is the most common, so anything else might confuse people. The form "Contract Law of the People's Republic of China" is also common, but that refers to a successor law, the 中华人民共和国合同法. "Commercial ..." would also be possible, but on Google there is only one result for that.

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Note added at 23 mins (2024-01-15 01:14:29 GMT)
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When translating propter names, such as the name of a specific law, it is a standard rule of the translating profession to use any standard or official translation, even if it is inadequate. Otherwise, for example, one could translate 中華人民共和国 as "People's Republic of Zhonghua" or "People's Republic of Central Hua", since "China" on its own, in English, is always translated as "中国", not as "中華".

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Note added at 2 hrs (2024-01-15 03:03:38 GMT)
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Yes, in general "commercial contract" describes the content of that law better than "economic contract", but the ethics of the translation profession forbid me to recommend that translation in the title of the law itself since a widely recognized English translation of the law's title already exists.