Abstract: In order to solve the problems existing in the solar greenhouse,the study took the northern Jiangsu region as an example,and screened four groups of materials such as n-butyl stearate（PCM1）,paraffin wax（PCM2）,paraffin wax and n-butyl stearate according to the mass ratio of 5∶5（PCM3）,90% Na2SO4·10H2O+2% borax+8% expanded graphite（PCM4）,and passed the differential scanning calorimetry test,thermophysical parameter determination test,thermal storage performance test and economic analysis,and used entropy weight method to evaluate multiple indexes,the results indicated that PCM3 ranked first with a relative preferential degree of 0.320. Then PCM3 was applied to the solar greenhouse without back wall,and the ordinary greenhouse without back wall was used as a control,and the experimental results showed that PCM3 can optimize the air temperature and soil temperature in the greenhouse,which can effectively reduce the temperature difference between day and night of the solar greenhouse,improve the temperature of the solar greenhouse at night,and optimize the thermal performance of the greenhouse.