Through experiment designed with the quadratic orthogonal rotation regression method of 4 factors such as density,N,P₂O₅ and K₂O.The results showed that:The effect of 4 factors influencing the yield of forage sorghum was N＞P₂O₅＞K₂O＞density,and the effect of N,P₂O₅ and K₂O was significant.Density and interaction effect between N and P₂O₅ reached significant or extremely significant level,the production of low density should be adding by P₂O₅ and N in order to get high yield.When density is high,the amount of N and P₂O₅ should be reduced appropriately to get higher yield,and the amount of N should be controlled appropriately under lower P₂O₅ level.Under high P₂O₅ levels,the yield could be effectively increased by increasing N level.Through computer simulation,the optimal cultivation scheme of fresh grass yield≥105,000 kg/ha under the condition of film-mulching in dry land is as follows:Density 128,000-133,000 holes/ha,N 217.26-240.30 kg/ha,P₂O₅ 183.28-200.60 kg/ha,K₂O 114.36-149.10 kg/ha.