Abstract: The aim is to study the relationship between genetic distance and heterosis, and to provide basic genetic theory for cucumber variety breeding. The materials consisted of five female parents, six male parents and their 29 F_l hybrids obtained by half diallel method. The heterosis analysis and cluster analysis were performed to study 7 quantitative characters of 11 cucumber germplasms. The correlation between genetic distances and heterosis was analyzed by using the 7 quantitative characters in cucumber. The results showed that the heterosis of all quantitative characters was positive. The heterosis of plant height, the number of yielded melons and the single plant yield was the most obvious, but the heterosis of single fruit weight, the number of female flowers, the length of fruits and the size of fruits was relatively weak. 11 cucumber germplasms were classified into 3 groups. There was no definite relationship between the geographic distance and the genetic distance. The relationship of genetic distance of plant height, the number of yielded melons, the single plant yield, the length of fruits and the size of fruits between parents and mid-plant heterosis and heterobeltiosis was highly significant. The heterosis of most characters increased with the genetic distance. To evaluate cucumber germplasms, geography origin should not be the only standard. Selecting parents with larger genetic distance might gain stronger heterosis.