Abstract: using experimental observation data of watermelon (Citrullus Lanatus) in solar greenhouse in Weifang Facility agricultural wisdom meteorological Service Demonstration Site from 2019 to 2021,based on fuzzy mathematical theory,a comprehensive suitability quantitative evaluation model and evaluation index of five factors,including air temperature,air humidity,solar radiation,ground temperature and temperature daily range,were established.The historical microclimate conditions of watermelon in solar greenhouse from 2019 to 2021 were evaluated and analyzed.The actual yield and quality of watermelon samples and typical disaster weather process were used to verify the applicability of the model and evaluation index.The results showed that the goodness of fit (R²) of the five-factor comprehensive microclimate suitability index and the comprehensive quality index is 0.6107,which is significantly better than the goodness of fit (R²) of the four-factor comprehensive microclimate suitability index and the comprehensive quality index (0.4079).The suitability model and evaluation index established in this study can well represent the suitability of microclimate environment during the growth and development of watermelon in solar greenhouse.The microclimate suitability of watermelon in solar greenhouse generally increased with growth and development,and the microclimate suitability of watermelon in solar greenhouse was higher in formation stage to maturity stage,but lower in transplanting stage and seedling stage.