In order to investigate the effects of mycorrhiza fungi and bradyrhizobium japonicum bacteria on the growth properties and yield of soybean cv. Katoul in different levels of phosphorus fertilizer, an experiment was conducted in a split-split-plots based on randomized complete blocks design with three replications at Agricultural Research Station of Gorgan in 2011-2012. The treatments were included: three levels of mycorrhiza (no inoculation, Glomus mosseae and Glomus intraradices), two levels use of bacteria and non-use of bacteria and three levels of net phosphorus (0, 1.32 and 2.64 g/m²). Results indicated that the effects of mycorrhiza and bacteria were significant in terms of all studies traits except plant number/m². Also, the effect of phosphorus was significant in terms of all studies traits except leaf dry weight and plant number/m². Binary interactive of treatments (mycorrhiza, bacteria and phosphorus) were significant only for leaf dry weight, leaf area and dry weight of nodules. Interactions effects of mycorrhiza × bacteria × phosphorus on leaf dry weight, leaf area, 1000 seed weight, number and dry weight of nodules were significant. According to data, the highest pod number in plant, seed number in pod and yield were observed in treatments of inoculation by Glomus intraradices, use of bacteria and 2.64 g/m² of phosphorus.