Abstract: In order to overcome season contradiction of the rapeseed-early season rice-late season rice cropping system in Jiangxi Province and ensure the high yield of the mode of rapeseed-early season rice-late season rice, a field experiment was carried out to study the effect of the mode rapeseed undersowing rice on growth and yield of rapeseed under the double cropping late rice field. The results showed that, the ontogeny of rapeseed undersowing rice was inhibited, rapeseed plants were thin, the number of pod and grain per pod, 1000 grain weight were relatively smaller comparing with no-tillage direct seeding after rice harvesting, but the number of rapeseed plants per hectare was the highest in all. It could take advantage of the growth superiority and get the highest yield, (1680.59 kg/hm²), which was 30.49% higher than the former. And it could get highest net benefit, 3044.95 yuan/hm², which was 2.3 times than the former.