Effects of the combined application of N,P,K fertilizer and rhizobium inoculant on yield traits, yield and economic benefit of soybean were studied by randomized block design. The results showed that OPT, OPT-N,OPT-K treatments improved the pods number per plant, seeds number per plant, grain weight per plant of soybeansignificantly, improved the soybean yield and economic benefit. OPT-N treatment had the highest yield with 4352.1 kg/hm², and net benefit was 18 075.1 yuan/hm². Compared with conventional fertilization, the yield increased by 29.4%, and net benefit increased by 5103.4 yuan/hm², so it brought higher profit for farmers.