| In order to investigate the effects of plant density on grain setting characteristics and grain yield of winter wheat. HG35 and JM22 (HG35 was a large-spike cultivar and JM22 was a multi-spike cultivar) were used in 2020-2021. Four densities were conducted as: 180×104 (D180), 300×104(D300), 420×104 (D420), 540×104 (D540) plants/hm2. The effect of densities on grain setting characteristics, grain spatial distribution and yield were studied. Results showed that the kernel numbers in upper spikelets of main stem and in basal spikelets of I tiller of HG35 were increased with the decrease in density. In addition, the kernel numbers in middle and upper spikelets of main stem and I tiller of JM22 were also increased with the decrease in density. Reducing density could effectively promote the grain setting of inferior florets in middle spikelets and superior florets in upper and basal spikelets. The kernel numbers in middle and upper spikelets of main stem of HG35 were higher than those of JM22. Meanwhile, the kernel numbers in the middle spikelets of I tiller of HG35 were also higher than those of JM22. The ear weight at anthesis was positively correlated with the number of fertile florets. In addition, the number of fertile florets and floret setting rate were positively related with kernel numbers, respectively. Results indicating the increase in spike weight at anthesis under low plant density provided sufficient nutrition for the development of florets to grains. There was no significant effect of plant density on 1000 grain weight. However, the spikes of HG35 decreased significantly with the increase in density. D300 achieved the highest grain yield. Whereas, there was no significant difference in yield between the four plant densities of each cultivar. In conclusion, properly reducing plant density saved cost, and realized green, high yield and high efficiency of winter wheat production by increasing kernel numbers on the basics of ensuring spikes at maturity.