You cannot change your surname at will. Changing your surname requires change registration.
According to the "Regulations on Household Registration of the People's Republic of China":
Article 18: Citizens' name changes shall be handled in accordance with the following provisions:
1. When a person under the age of 18 needs to change his or her name, the person or his/her parents or adopter must apply to the household registration authority for change registration; At that time, I shall apply to the household registration authority for change registration.
Extended information
The "General Principles of the People's Republic of China and the Civil Law" stipulates:
Article 99 Citizens enjoy the right to name and have the right to decide , use and change your name in accordance with regulations, and prohibit others from interfering, misappropriating or counterfeiting.
Legal persons, individual industrial and commercial households, and individual partnerships enjoy the right to name. Corporate legal persons, individual industrial and commercial households, and individual partnerships have the right to use and transfer their names in accordance with the law.
Article 120 If a citizen's right to name, portrait, reputation, or honor is infringed upon, he or she has the right to demand an end to the infringement, restoration of reputation, elimination of the impact, apology, and compensation for losses. .
If a legal person’s right to name, reputation, or honor is infringed upon, the provisions of the preceding paragraph shall apply.
The "Marriage Law of the People's Republic of China" stipulates:
Article 22: Children can take their father's surname or their mother's surname.
China National People's Congress Network - Household Registration Regulations of the People's Republic of China