The government purchases service substitute teachers, which refers to handing over the services provided by the government directly to the public to qualified social organizations or market institutions, and paying service fees after evaluating the quantity and quality of services provided by social organizations or market institutions. Its original intention is to "guarantee the provision of basic public services", which belongs to an administrative obligation.

Other situations are as follows:

1. Theoretically, the inefficient supply of public services under government monopoly is the basic basis for the government to purchase public services.

2. In practice, the government's practice of purchasing public services originated in modern western countries and prevailed in the second half of the 20th century. It is also one of the core orientations advocated by western new public management theory and practice since 1980s.

3. The 18th National Congress of the Communist Party of China emphasized the need to strengthen and innovate social management and improve the way the government provides public services. The State Council explicitly demanded that public services should make more use of social forces and the government should purchase more services. Education is an important part of public service. It is also the responsibility of local governments at all levels to solve the shortage of rural teachers and provide quality education services for rural students by purchasing social services.

4. To implement the government's purchase of services and solve the problem of substitute teachers, we must first clarify the service content and implement the purchase items item by item. This requires the education authorities at all levels to refine, decompose and determine the positions of teachers' services, find out the number and structure of teachers urgently needed in each school, and ensure that the educational services purchased by the government can meet the needs.