Effects of different planting densities on population structure and yield were studied under the condition of moist film mulching using Jihong 6, a large-scale rice variety planted in Jilin Province. The results showed that plastic film mulching could increase the effective accumulated temperature during the rice growth period significantly and promote the early growth and rapid development of rice. Among the 5 density treatments, the yield of 3 treatments with row spacing of 30 cm×13.33 cm (T₁), 30 cm×16.67 cm (T₂), 30 cm×20.00 cm (T₃) exceeded 500 kg/667 m², and the yield of T₁ was the highest, reaching 592.09 kg/667 m². T₁, T₂ and T₃ had larger LAI, more dry matter accumulation, more effective panicles per unit area, and also reached high yield. T₅ treatment had more tillers per hole, but less effective tillers per unit area and low yield. The results showed that, on the premise of obtaining higher yield, population structure and lodging phenomenon, the optimum transplanting density of rice under the condition of wet film mulching is (30 cm×16.67 cm) - (30 cm×20.00 cm).