No. In the international phase, the language is prescribed by the receiving office of the PCT with which you have chosen to file your application. When China is the receiving Office, both English and Chinese are acceptable. However, after entering into the national phase, the application must be translated into Chinese. According to the Law, if a PCT application filed in a language other than Chinese has designated China, the applicant should provide a Chinese translation to SIPO within 20 months from the date of priority.