Soybean is a phosphorus-loving crop， whereas phosphorus deficiency can affect soybean growth and development finally resulting in yield loss. The grain weight per plant of soybean is a quantitative character， which is an important indicator for identifying soybean tolerance to low phosphorus. At present， most studies are still in the stage of QTL mapping， so it is particularly important to discover more regulatory genes and excellent allelic variations in order to promote the analysis of the regulatory mechanism of soybean tolerance to low phosphorus and its breeding utilization. In this study， 395 soybean germplasm resources were used to conduct genome-wide associated study （GWAS） and preliminarily predict candidate genes by using grain weight per plant under low phosphorus and relative conditions as identification indicators for low phosphorus tolerance traits， combined with high-density SNP markers. The results showed that the tolerance to low phosphorus was significantly different among different soybean germplasms. The grain weight distribution per plant of normal phosphorus was 0.49 ~ 14.43 g， the grain weight distribution per plant of low phosphorus was 0.05 ~ 5.35 g， and the relative grain weight distribution per plant was 0.04 ~ 0.98. The coefficients of variation of the three were all higher than 50%. Through cluster analysis， 4 landraces such as Yapoche（ZDD00219） and Caizhongpu（ZDD00163） and 16 cultivars such as Jinyuan 1 （ZDD00383） and Jiyu 48（ZDD23714） were screened as phosphorus efficient soybean germplasms. GWAS identified 32 SNP loci significantly associated with low phosphorus tolerance of soybean， including 23 SNP loci associated with single plant grain weight under low phosphorus and nine SNP loci associated with relative single plant grain weight. Two candidate genes were proposed by LD block analysis， including a WRKY DNA binding domain gene that was detected with specific expression in roots， and a pyridoxal phosphate phosphatase gene that was detected with specific expression in root hairs.