This is illegal. The Education Bureau clearly stipulates that in-service teachers can't make up lessons for students privately during the holidays, which means that they can't run cram schools during the summer vacation. Article 75 of the Education Law of the People's Republic of China stipulates: According to the past situation, all in-service teachers have used the winter and summer vacations to run classes without the approval of the Education Bureau, because teachers have the right to rest and participate in training, and these rights of teachers should be guaranteed during holidays. Therefore, it is basically illegal for in-service teachers to use holidays to run classes, which should be strictly prohibited. What has been done should be banned.

the education law of the peoples republic of china

Article 31 The sponsors of schools and other educational institutions shall, in accordance with the relevant provisions of the state, determine the management system of the schools and other educational institutions they run. Principals or principal administrators of schools and other educational institutions must be China citizens who have settled in China and have the qualifications prescribed by the state, and their appointment and removal shall be handled in accordance with the relevant provisions of the state. The headmaster is responsible for the teaching and other administrative management of the school. Schools and other educational institutions shall, in accordance with the relevant provisions of the state, ensure that the teaching and administrative staff participate in democratic management and supervision through organizational forms such as teachers' congresses.

Article 33 Teachers shall enjoy the rights prescribed by law, perform their obligations prescribed by law and be loyal to the people's educational cause.