Abstract: In order to select the heat-tolerant soybean germplasms and establish efficient and convenient evaluation system during the germination stage. 1 124 varieties（lines） including the released cultivars in South China and main breeding germplasm of Guangxi were selected to test the seed germination rate at 25 and 38 ℃, respectively. Then we used the relative germination rate at 38 ℃/25 ℃ to evaluate the high-temperature tolerance of soybean at germination stage, discussed the correlation between the morphological traits, specific gravity, bulk density, quality traits of seeds and the relative germination rate, and select optimal index for seed heat tolerance screening. The germination rate of soybean decreased at high temperatures, and there was a significant difference in germination rate among different varieties. 78 high heat-tolerant germplasm were screened out by the relative germination rate, and three varieties including Du′anqingpidou, Nandou 35, and 14-Xia-G8-65 had a relative germination rate of 100%. Moreover, the percentage of heat-tolerant germplasm in spring soybean was significantly higher than that of summer soybean, and the percentage of heat-tolerant germplasm in non-yellow seed coats was higher than that of the yellow seed coat.Correlation analysis showed that the heat tolerance of soybean at the germination stage was negatively correlated with seed shape index, surface area, 100-seed weight, and protein content, but significantly positively correlated with bulk density and specific gravity. Stepwise regression and path analysis showed that the heat tolerance of soybean at the germination stage was closely related to the seed shape index, 100-seed weight, bulk density, and specific gravity. The bulk density of soybean seeds was positively correlated with seed shape index and specific gravity, and negatively correlated with 100-seed weight. Therefore, it was suggested that the bulk density could be used as the primary evaluation index for the heat-tolerant soybean germplasm.