Phosphorus is one of the 17 essential elements for plant growth and the most limiting element after nitrogen for plant growth. It has a significant role in many vital processes such as photosynthesis, respiration and structure of nucleic acids and cell structure. Phosphorus absorption capacity due to the high pH and the abundance of calcium is less than the sufficient amount for proper growth of plants, in many soils of Iran. On the other hand, about 80% of phosphorus fertilizers used in the soil is in the stabilized forms and unavailable to the plants. Therefore providing ways to improve the efficiency of these fertilizers on agricultural land is necessary. The use of soil microorganisms that are able to dissolve the phosphate is, one of the appropriate ways to increase the absorption of phosphorus in the alkaline soil. Thus, the present study was performed to investigate the effect of phosphate solubilizing strains on the availability of phosphorus in corn, selection and identification of superior strains (first test), effect of the best three bacteria together with arbuscular mycorrhizal fungi on growth characteristics of maize (second test). for the first test 24 phosphate solubilizing isolates were prepared from the Biology Department of Soil and Water Research Institute, Iran and initial tests and resistant tests to high temperatures (45 and 50 degrees C) and different pH were done. Treatments were 24 treatments with phosphate solubilizing isolates, three blanks (blank A: treatment without microbial inoculation, blank B: treatment without plant and microbial inoculation and blank C: treatment without microbial inoculation and nutrient solution) and a control+ (containing triple super phosphate), respectively. The experiment was performed in a Leonard Jar and three maize seeds cv 704 were planted, at the depth of 5 cm of sand bed in each jar2g rock phosphate was mixed with the beds of all treatments except control+. For control+ 1g triple super phosphate fertilizer (in powder form) was mixed with the bed. This experiment was conducted in a randomized complete design with four replications in a growth chamber and greenhouse Soil and Water Research Institute. Shoots were harvested after 65 days of planting and root and shoot fresh and dry weights, phosphorous concentration and absorption in aerial parts and bed were measured. Finally based on the results, three bacteria were chosen and identified by molecular methods. In a second experiment the effect of bacterial treatments three treatments with best three bacteria, one treatment with mixture of three bacteria and one treatment without bacteria), two fungal treatments (treatment with Rhizophagus irregularis and treatment without mycorrhiza), two blank (blank A: without microbial inoculation blank B: without microbial inoculation and plant cultivation) and a control+ (containing fertilizer triple super phosphate) were evaluated. Three seeds of maize cv 704 were planted at a the depth of 5 cm of soil in pot culture experiments. A Factorial experiment was done based on completely randomized design with 4 replications. After 60 days, leaf chlorophyll content height, shoot and root fresh and dry weights, length, percentage of root colonization and concentration and uptake of P in aerial parts were measured after harvesting. In the first test, the results showed that among all isolates, Azoto-5 and B-Coa had the highest tolerance when the temperature increases and isolates Th had an ability to reduce the pH of the liquid medium. In the jar system, the control + showed higher P uptake and growth characteristics than other microbial treatments. According to the results of the first experiment, three bacteria Th (Lactobacillus plantarum), 46J (Pantoea vaqans) and C5-1 (Rahnell sp.) were selected as bacteria. The second study showed that there were no significant difference between fungal treatments and treatments without fungi in plant growth characteristics and P uptake by aerial parts. But the presence of the fungus increased root colonization percentage and reduced the amount of chlorophyll. Different treatments of bacteria didn’t show significant differences associated with growth characteristics (except shoot dry weight) and shoot phosphorus uptake. Among microbial treatments, the highest phosphorus in aerial parts was seen by B0F1 (without bacteria and with fungi) In general, plants treated with bacteria had the higher amount of phosphorus in aerial parts than treatments without bacteria. Among four treatments containing with fungi and bacteria, interaction between C5-1 bacterium and mycorrhizal fungus was positive and shoot and root dry weight, root volume, root length, chlorophyll, phosphorus, shoot phosphorus uptake were higher than those in other treatments. Keywords : Phosphorus, rock Phosphate, Phosphate solubilization bacteria, Mineral solubilizers, corn and arbuscular mycorrhiza fungi.