With 200 melon germplasm as the research object, SSR molecular marker data were used for genetic diversity analysis, and stepwise unweighted pairwise arithmetic mean(UPGMA) clustering was performed on the genetic similarity coefficients, and multiple sampling was used to construct a core germplasm library of melon. The results showed that a total of 109 polymorphic loci were amplified by 35 pairs of SSR markers, the average number of alleles(Na), the number of effective alleles(Ne), the observed heterozygosity(Ho), the expected heterozygosity(He), polymorphism information content(PIC), and the Shannon index(I) were 3.11, 2.60, 0.37, 0.57, 0.49, 0.96, respectively. Cluster analysis based on UPGMA categorized the 200 germplasm into 2 major groups. Genetic structure analysis showed that Δk was the largest when K=2, and the tested germplasm could be divided into 2 subgroups, which was consistent with the clustering results. The genetic diversity indices of each core subset constructed did not change significantly in general, and a sampling ratio of 10.0% was finally established, containing 20 core germplasm of melon varieties(species), of which the Na retention rate was 98.17%, the Ne retention rate was 99.42%, the I retention rate was 99.79%, the Ho retention rate was as high as 104.08%, the He retention rate was 100.35% and the PIC retention was 99.59%. The t-test and principal coordinate analysis showed that there was no significant difference between the genetic diversity parameters of the core germplasm and the original germplasm, and the genetic diversity of the original germplasm could be adequately represented.