Abstract: The paper aims to explore the optimum planting density of rapeseed in no-till low latitude mountain areas. By using grey relation analysis and fuzzy cluster analysis, agronomic traits and yield of ten planting densities of rapeseed grown in no-till mountain areas with 4 different latitudes were compared in 2013-2015 in Yuxi. The results showed that: (1) with the increase of planting density, the lodging index rose, and the growth period, frozen percentage, frozen index, incidence of powdery mildew and disease index had an increasing trend, however, bird damage percentage and bird damage index appeared a decreasing trend; (2) the main agronomic traits were significantly different due to the difference of planting density, the number of effective pods per plant and productivity per plant decreased with the rise of planting density, seeds per pod and thousand-seed weight declined to different degrees as well; (3) there were varied associations between main agronomic traits and the planting density; (4) the yield under different planting densities varied a lot. The optimum planting density of 300-360 thousand plants per hectare is recommended for the low latitude no-till mountain areas.