Abstract: Abstract: In order to improve the thermal environment of crop growth in solar greenhouse, a kind of gypsum-based paraffin/expanded perlite composite phase change energy storage thermal insulation mortar was studied in this paper. The composite phase change energy storage thermal insulation mortar was composed of complex shaped phase change particles, desulfurization gypsum, admixture and other components, and the reasonable formula and the production process of it were determined by experiments. The composite phase change energy storage thermal insulation mortar with reasonable formula had a suitable phase transition temperature of 25.6 ℃ and a higher phase change latent heat of 89.8 kJ/kg. The 50 mm composite phase change thermal insulation mortar was used in the back wall of the brick wall solar greenhouse as the experimental greenhouse. The original brick wall solar greenhouse without phase change material was used as the comparative greenhouse. The comparison test of these 2 greenhouses showed that: From December 10, 2015 to February 18, 2016, the minimum daily temperature of the experimental greenhouse was 1.5 ℃ higher than that of the comparative greenhouse on the average, and the difference reached 2.4 ℃ at the most. On overcast day, the heat preservation quilt was closed, and the indoor temperature of the experimental greenhouse was 1.6 ℃ higher than that of the comparative greenhouse. On sunny day, the indoor maximum temperature of the experimental greenhouse and the comparative greenhouse was 28.9 and 30.6 ℃, respectively, and there was 1.7 ℃ difference between the two greehouses. The indoor maximum temperature difference of the experimental greenhouse and the comparative greenhouse was 21.3 and 24.4 ℃, respectively, and the former was 3.1 ℃ lower than the latter. During the night (from 17:00 to 08:00 in the next day), the average indoor temperature of the experimental greenhouse was 2.7 ℃ higher than that of the comparative greenhouse. On cloudy day, the indoor maximum temperature of the experimental greenhouse was 1.4 ℃ lower than that of the comparative greenhouse; the indoor maximum temperature difference of the experimental greenhouse and the comparative greenhouse was 20.4 and 23.9 ℃, respectively, and the former was 3.5 ℃ lower than the latter. During the night (from 17:00 to 8:00 in the next day), the average indoor temperature of the experimental greenhouse was 2.3 ℃ higher than that of the comparative greenhouse. Under the same cultivation and management conditions, in the vigorous growth period and fruit-bearing stage, the height of cucumber plants in the experimental greenhouse was 17.1 and 24.6 cm higher than that of the comparative greenhouse. The single-fruit quality of the cucumber in the experimental greenhouse was 1.4 times that of the comparative greenhouse, the number of fruits per plant in the experimental greenhouse was 1.3 times that of the comparative greenhouse, and the output of per plant in the experimental greenhouse was 1.8 times that of the comparative greenhouse. The test results show that, the composite phase change energy storage thermal insulation mortar has a good heat preservation and storage and release effect, and has an obvious improvement effect on the thermal environment in solar greenhouse. The thermal environment in the experimental greenhouse is more suitable for the growth of cucumber.