The solar greenhouse is only greenhouse type for China. Indoor thermal environment of solar greenhouse is improved via the heat storage and heat release of wall body. The soil wall body, which has good characteristic of heat storage and heat release, is applied to solar greenhouse extensively in China. The thickness of soil wall body is determined by the builder’s experience due to lack construction standards. At present, the study on the heat release characteristic of different thicknesses soil wall is hot spot, which can provide the theoretical basis for the simplification and thickness optimization of soil wall body. The solar greenhouse No.1 (the top and bottom width of the soil wall body was 2.0m and 6.0m, respectively) and solar greenhouse No.2 (the top and bottom width of the soil wall body was 1.3m and 3.0m, respectively) were chosen as research object in Tai’an, Shandong Province, China. The greenhouse No.1 and No.2 had the same length (50.0m) and width (10.0m). Five testing layers of temperature at the same height of the north wall of both greenhouses were arranged. The testing period was from Dec. 20th, 2015 to Jan. 20th, 2016. The outdoor weather conditions, indoor air temperature and interior wall temperature in the sunny day (from Dec. 30th, 2015 to Jan. 2th, 2016) and cloudy day (Jan. 4-6th, 2016) were used to analyze the temperature distribution and the heat release characteristic of each testing layer in the greenhouses No.1 and No.2. The results showed that during the sunny day, the heat storage and release quantity of the greenhouse No.1 was higher than that of the greenhouse No.2, but the difference was little, which was 82.3kJ and 45.0kJ, respectively. For the three cloudy days, the heat release characteristic of wall body of the solar greenhouses No.1 and No.2 was analyzed based on the data of the wall body temperature and indoor temperature. The results showed that the heat release quantity of greenhouse No.1 was higher than that of the greenhouse No.2, the difference was 615.9kJ, but the air temperature of the greenhouse No.1 was only 0.6℃ higher than that of the greenhouse No.2 during the cloudy day. The analysis of relative temperature stability part of wall showed that the heat storage of the greenhouse No.1 was very higher than that of the greenhouse No.2. This heat relative temperature stability part for the thick wall greenhouse should be used via efficient heat exchange equipment to improve the thermal environment of greenhouse.