In order to solve the problems of low temperature inside the greenhouse caused by continuous haze weather or cloudy, rainy, and snowy weather, as well as the large heat dissipation capacity and insufficient cross time heat storage of existing solar greenhouses, by optimizing the design of the external insulation materials and structure of the heat storage water tank and studying the combination of heat storage working fluids, the greenhouse heat storage device has achieved cross time heat storage and segmented slow release heat release. The experiment shows that the combined heat insulation effect of heat insulation coating + aerogel + rubber and plastic insulation cotton is better, its 24-hour heat dissipation is reduced by 0.367 MJ compared to a single insulation material. The heat preservation material of the tank is 80~120 mm, and the cylinder heat storage tank is 6~10 m3 and 1:1. Which cannot only ensure a low effective heat dissipation rate, but also control engineering. The results show that the composite phase change material can increase the heat storage capacity, optimize the exothermic process, and achieve the gradual release of heat.