You can't change your surname at will, and you need to register for change.

according to the regulations of the people's Republic of China on household registration:

article 18? Citizens who change their names shall be handled in accordance with the following provisions:

1. When a person under the age of 18 needs to change his/her name, he/she or his/her parents or adopters shall apply to the household registration authority for registration of change; ?

when a person over the age of 18 needs to change his/her name, he/she shall apply to the household registration authority for registration of change.

Extended information

The General Principles of the People's Republic of China and the Civil Law of the People's Republic of China stipulates:

Article 99 Citizens have the right to name, have the right to decide, use and change their names according to regulations, and are prohibited from interference, misappropriation or counterfeiting.

legal persons, individual industrial and commercial households and individual partnerships enjoy the right to name. Enterprise legal persons, individual industrial and commercial households and individual partnerships have the right to use and transfer their names according to law.

article 12 if a citizen's right to name, portrait, reputation and honor is infringed, he has the right to demand that the infringement be stopped, his reputation be restored, the influence be eliminated, he makes an apology, and may demand compensation for losses.

if the right of name, reputation and honor of a legal person is infringed, the provisions of the preceding paragraph shall apply.

The Marriage Law of the People's Republic of China stipulates:

Article 22 A child may take his father's surname or his mother's surname.

China people's congress net-regulations on household registration of the people's Republic of China.