Abstract: To find out the suitable sowing date and planting density for winter oats in Yunnan, 3 oat cultivars of ‘Baiyan No.15’,‘Bayou No.6’and‘Yuanza No.2’with different growth periods were used as experimental materials. The single factor randomized block design was used to study the effects of 3 types of sowing dates and planting densities on the main economic traits and yield of winter oat. The results showed that the main spike spikelet number and the spike wheel layer of‘Baiyan No.15’and‘Bayou No.6’were significantly influenced by the sowing date (P＜0.05) ; however, there was no significant influence on the other economic traits of the 3 cultivars (P＞0.05). The tiller number per plant and the effective tiller number per plant were significantly influenced by the density (P＜0.05) and the influence on other traits was not obvious (P＞0.05). According to the yield result, the optimized treatments are as follows: the suitable sowing date of‘Baiyan No.15’ is on October 29th, with the density of 6.4×105 lants/hm2; the suitable sowing date of‘Bayou No.6’is on October 14th, with the density of 6.4×105 plants/hm2; the suitable sowing date of‘Yuanza No.2’is on October 14th, with the density of 4.8×105 plants/hm2.