In order to evaluate drought stress and arbuscular mycorrhiza with phosphorus on related root and shoot traits and grain yield of mungbean, a factorial experiment was carried out based on a randomized completely design in pot culture. Irrigation regimes 25, 50, 75 and 100mm of evaporation from a pan possessed irrigation's levels as the first factor. At the second factor arranged 5, 15mgPKg-1 soil and 5, 15 with Glomus mosseae with three replications were conducted in Urmia University in 2010. Results showed that grain yield of inoculated mungbean with 15 and 5mgPKg-1 soil 834.17 and 699.317mg/plant had the highest values, respectively. Both 15 and 5mgPKg-1 soil with G. mosseae had more leaf phosphorus, plant height, leaf number, leaf dry weight, pod number, seed/pod, root dry weight, root length, root volume, and chlorophyll index than 15 and 5mgPKg-1 soil non-inoculated plants. Leaf phosphorus, plant height, leaf number, leaf dry weight, pod number, seed/pod, root dry weight, root length, root volume, and chlorophyll index had positive correlation coefficients with grain yield. The highest (743.33mg/plant) and lowest (423.33mg/plant) grain yield achieved in irrigation after 25 and 100mm evaporation, respectively. With increasing water deficit stress decreased leaf phosphorus, leaf number, leaf dry weight, seed/pod, root dry weight and chlorophyll index. Although drought stress reduced grain yield, but inoculated it reduced the severity of stresses. Inoculated plants increased 69% of the potential yield than control.