Legal basis:
People's Republic of China (PRC) Prison Law
Article 47 A prisoner may correspond with others while serving his sentence, but his correspondence shall be subject to inspection by the prison. Letters found in prisons that hinder the reform of criminals may be detained. Letters written by criminals to higher authorities and prison judicial organs are not subject to inspection.
Article 48 While serving a sentence, a prisoner may meet with his relatives and guardians in accordance with regulations.