Abstract: 【Objective】To investigate the difference of grain weight and seed vigor among different parts of different rape varieties; 【Method】Five rapes were selected to study by randomized blocks experiment and simplified vigor index method, the grain weight of the different parts of the same variety was significantly different; 【Results】The grain weight of the same part of the different varieties was also different. A stub rape was divided into the bigger seed area, the middle seed area and the smaller seed area by seed weight; the relation of the grain weight of the different parts and seed vigor was significant. The seed vigor of three areas were reduced from big seed area to smaller seed area; 【Conclusion】The seeds of rape stem and some first effective branches were the bigger seed area which was the best area for rape seed selection and seed stock, and its seed vigor was the highest.