Can China people engage in overseas agency in Thailand?

Yes, you can. Thailand is a member and founding member of the Association of Southeast Asian Nations, as well as a member of the Asia-Pacific Economic Cooperation and the World Trade Organization. China people can set up foreign institutions in Thailand. The Kingdom of Thailand, referred to as Thailand for short, is located in the south-central Indochina Peninsula, bordering the Gulf of Thailand in the Pacific Ocean in the southeast and the Andaman Sea in the Indian Ocean in the southwest.