Abstract: The study observed heat release of soil back wall and ground of solar greenhouse, and measured surface heat flux of soil back wall both in sunny days and cloudy days in Shangdong-5(sd-5) and Ningxia-2(nx-2) greenhouses. The result showed that sd-5 greenhouse’s heat release of per unit wall area is significant greater than nx-2 greenhouse’s, and sd-5 greenhouse’s ground surface heat release of per unit ground area is less than nx-2 greenhouse’s, no matter in short time or long term. The sd-5 greenhouse’s total amount heat release was 9.9% greater than the nx-2 greenhouse’s in long term. The sd-5 greenhouse’s heat release of wall was 34% greater than its ground, the nx-2 greenhouse’s heat release of ground was 2% greater than its wall in long term.