Genetic analysis of multi-leaflet trait were conducted by four crosses from 4 normal female parents with 3-leaflets and one mutantal male parent with five-leaflet which is derived from 5th selfbred of cross Hefeng25×Dongnong7296. All leaves of F1 individual have 5 leaflet in 4 crosses, which indicated that 5-leaflet is dominantly controlled by nuclear genes. The segaration mode of 3-leaflet, 3+4-leaflet, 3+5-leaflet, 3+4+5-leaflet, 4+5-leaflet and 5-leaflet were different according to crosses in F2. While the inheridtary pattern of 3-leaflet and >3-leaflet were coherent in various genetic background with a segarating ratio of 1:3, which means that leaflet traits follows one dominant gene inheridity. Leaflet were controlled by one dominant gene and the new soybean mutant germplasm Mu5796-3 can be used in soybean breeding and gene cloning.