To be able to work legally in China, foreign workers must have: (i) a work permit linked to a specific employer, and (ii) a residence permit for work purpose. Foreign students are not eligible to obtain such permits, but enjoy some flexibility to do internships in mainland China:

• Foreign students studying in Chinese universities with an X1 visa can undertake internships if they meet specific requirements. They must be enrolled in a qualified university, gain approval from their institution, obtain a study resident permit, and receive an official endorsement from the Exit-Entry Bureau. Internships must align with their major, be limited to one at a time, and not exceed 180 days without re-registration. Students on an X2 visa must convert it to an S2 visa to qualify. Non-compliance can lead to fines and disciplinary action.
• Foreigners studying in foreign universities and based abroad can enter China on Z visas for internships under inter-governmental agreements can apply for a residence permit for work marked as “Internship.” They must provide essential documents, including a valid passport, visa application form, recent photograph, health certificate, an application letter from their organization, and business-related permits. The exit-entry administration may request additional documents, interviews, or proof of financial support as needed. Decisions made by the administration regarding permit applications are final and cannot be appealed.

It is strongly advised not to enter China for work through the 30-day visa-free policy, or on other categories of visas, such as tourism or business. Although this used to be a common practice, it is illegal and can lead to detainment and even deportation (and consequent multi-year ban from re-entering China).