Six self-lines of bitter gourd were divided into two groups and 9 crosses were made by incomplete diallel cross. Genetic distance of principal components was calculated by using 11 quantitative characters. Using genetic distance as independent variable and heterosis as dependent variable, we carried out regressing analyses. The results showed that there was a significant linear relationship between genetic distance and yield heterosis and a very significant linear relationship between genetic distance and fruit length heterosis, and their regression equation were Y=7.5718+3.2272X and Y=-5.8529+1.5946X,respectively. Relationships between individual fruit mass and fruit width heterosis and genetic distance weren’t found in this study. Individual fruit mass was an important constituent character of yield, while leafstalk length and node length were two important constituent characters of fruit length. Applied outlook of genetic distance to forecast heterosis was discussed in this paper. Further research should be conducted for genetic distance to forecast heterosis.