Taking Semen Cassiae as material,using randomized block design,the effect of 5 planting density of Semen Cassiae on the grain yield,economic characters,economic benefit of it was studied.The results showed that grain yield with planting density of 120 000 cassias/hm2 was very significantly higher than the other four kinds of planting density of grain yield.Planting density of 97 500 cassias/hm2 and 142 500 cassias/hm2 grain yield were significantly higher than the planting density of 75 000 cassias/hm2 and 165 000 cassias/hm2.Among them,the grain yield of planting density of 120 000 cassias/hm2 increased by 700.5,409.5,430.5,736.5 kg than the other four density per hm2 respectively.The economic benefit of density of 120 000 cassias/hm2was the highest,respectively than the other four planting density per hm2increased by 7 005,4 095,4 305,7 365 yuan.Comprehensive consideration,the optimum planting density of Semen Cassiae was 120 000 cassias/hm2