Abstract: The study observed heat release of soil back wall and ground of greenhouse, and measured surface temperature and heat flux of soil back wall both in sunny days and cloudy days. The result showed that heat release of per unit wall area and ground surface had a close relationship with solar radiation in greenhouse. The heat release of per unit wall area was 1.90 MJ/m2 at night in sunny days, and the heat release of ground was 1.36 MJ/m2; while the heat release of per unit area was 0.76 MJ/m2 at night in cloudy days, and the heat release of ground was 1.34 MJ/m2. During sunny days, the heat release of wall was greater than that of ground, while the heat release of ground was greater than that of wall in cloudy days. No matter it is on sunny days or cloudy days, the total amount of heat release was greater than that of wall, moreover, the ground buffer of cycle heat changing is better than the wall.