Abstract: In order to investigate the effects of sowing date and planting density on photosynthetic characteristics, yield and its yield components of spring soybean in Southern Xinjiang, four sowing dates B1（April 7）, B2（April 17）, B3（April 27） and B4（May 7）, and three densities M1(510 200 plants ·ha^-1), M2(308 600 plants ·ha^-1) and M3(226 800 plants ·ha^-1) were adopted. The effects of sowing date and planting density on growth process, leaf area index, photosynthetic characteristics, dry matter accumulation, yield and yield components of spring soybean were determined. The results showed that compared with B1 treatment, B4 prolonged the growth period by 6.3 days, but shortened the R4-R6 stages by 10.7 days. The LAT of B4 at R6 stage was significantly lower than that at other sowing dates, and the increase of planting density at each sowing date could significantly increase the LAI. At R4 stage, the net photosynthetic rate（NPR） of B1 was 29.75%, 23.09% and 39.40% higher than that of B2, B3 and B4 respectively, and the NPR and transpiration rate were still higher at R6 stage. The dry matter accumulation in R4 stage increased gradually with the delay of sowing date, and the dry matter accumulation in M3 plant increased significantly, while the dry matter accumulation in R6 stage was contrary. Late sowing and increasing planting density would reduce the branches pods number, branch seeds number and branch seeds weight, thus reduce the yield. In conclusion, in the treatments of this study, early sowing and decreasing planting density could ensure sufficient development time and strong photosynthetic capacity of soybean leaves in R4 and R6 stages, maintain the R6 period had higher leaf area index, dry matter accumulation, and increase the branches pods number, branch seeds number and branch seeds weight, thus significantly improve yield.