In order to investigate the effects of planting density on grain setting characteristics and grain yield of winter wheat,Hengguan 35(a large-spike cultivar) and Jimai 22(a multi-spike cultivar) were used in 2020-2021. Four densities were conducted: 1.8×10⁶(D180),3.0×10⁶(D300),4.2×10⁶(D420),and 5.4×10⁶(D540) plants·hm^-2. The effect of densities on grain setting characteristics, grain spatial distribution and yield were studied. The results showed that the kernel number in upper spikelets of main stem and in basal spikelets of I tiller of Hengguan 35 increased with the decrease of planting density.In addition, the kernel number in middle and upper spikelets of main stem and I tiller of Jimai 22 also increased with the decrease of density.Reducing density effectively promoted the grain setting of inferior florets in middle spikelets and superior florets in upper and basal spikelets. The kernel number in middle and upper spikelets of main stem of Hengguan 35 was higher than that of Jimai 22. Meanwhile, the kernel number in the middle spikelets of I tiller of Hengguan 35 was also higher than that of Jimai 22.The ear weight at anthesis was positively correlated with the number of fertile florets. 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 1 000-grain weight. However, the spikes of Hengguan 35 decreased significantly with the increase of 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 number on the promise of ensuring spike number at maturity.