Not less than 25 degrees. By July 17, 2023, according to the regulations of Changchun Agriculture Bureau on greenhouse slope, the greenhouse type in Changchun should be reasonably selected according to the local climate conditions, cultivation season, production level and economic base, and the slope between the top surface and the ground should not be less than 25 degrees, which is one of the key measures to ensure high yield, high quality and high efficiency of greenhouse vegetables.