You can try to apply in Thainland, but no one here can assure you with that you may need to apply in your home country. Visa officers are empowered to decide your visa type, but you can write your request for multiple entry to the applicaiton form. The required documents are your passport valid for more than 6 months, applicaition form for China with photo stuck to it, round trip ticket and hotel bookings from China. Proof of financial support may be required if visa officers deem necessary.