Abstract: To explore the influence of planting density on yield and yield composition of tartary buckwheat [Pagopyrumta taricum (L.)] of late sowing cultivation in Yunnan, we took ‘Yunqiao 1’ , which accounted for the largest planting area in the province, as the material to conduct the test. The design included 4 different densities (7.0×10⁵, 9.5×10⁵,12.0×10⁵,14.5×10⁵ plants per hm²) of tartary buckwheat. The results showed that: in late sowing cultivation, planting density had no significant effect on the botanic characters such as plant height, first branch number, node number of main stem, but there were significant differences in yield; yield of 14.5×10⁵ plants/hm² planting density was the highest, up to 2424.17 kg/hm². Therefore, the most suitable planting density of ‘Yunqiao 1’ in Yunnan autumn sowing area is 14.5×10⁵ plants/hm².