The film is about under the background of great migration and urbanization in China, this film focuses on the troubles in migrant workers' life due to household registration system. Because of the household registration system, although the Chinese government allows people in rural or poor areas to move to developed or large and medium-sized cities, the migrants actually have not been treated fairly as their children cannot even study in the city where they work.And their schools were demolished, they were expelled from the big cities.