Abstarct: To study the effect of mycorrhizal fungi inoculation and phosphorus fertilizer application on growth traits and yield of corn in competition with weeds, a field experiment was conducted at the Research farm of Shahrood University. Treatments were the factorial arrangement of mycorrhizae (inoculated with Glomus mussea and non-inoculated), phosphorus fertilizer (triple superphosphate source) at three levels (non-application, application of 25 and 40 kg of phosphate fertilizer per hectare) and weeding with three levels (weeding all season, no weeding all season and cultivating Chenopodium album). The results showed that compared with control, inoculation improved the traits studied. In terms of weeding, inoculation and application of 25 kg of phosphorus corn yield increased by 67% compared to non-inoculated and non-application of phosphorus fertilizer in the presence of C. album. Biological yield increased by 44% for weeding + fertilization compared with non-inoculation states. The highest positive effect was found for weeding× inoculation×25 kg P by which the 100-seed weight increased by 45.13%. No weeding× inoculation decreased weed biomass by 32%. No weeding×inoculation×40 kg P diminished the total number of weeds by 52.84%. Mycorrhizal fungi significantly increased the percentage of phosphorus in corn and soil by 60.97 and 26.70%, respectively, compared to noninoculated case. Generally, mycorrhizal inoculation increased P uptake and water and subsequently enhanced the growth and ability of corn to compete with weeds.