Abstarct: Arbuscular mycorrhizal (AM) fungi are ubiquitous components of many ecosystems and can colonies two-thirds of all plant species. In order to evaluate effects of dual inoculation of arbuscular mycorrhizal(AM) fungi and Mesorhizobium bacteria on the Yield and Yield components of maize-cowpea intercropping system, an experiment was carried out as randomized complete block design (RCBD) with three replications at research field of faculty of agriculture, Shahrood University of Technology in the growing season at 2010. Experimental treatments were included monocropping of maize, monocropping of Bean and maize-bean intercropping baxsed on additive series (100% maize and 100% beans), monocropping of maize + Mycorrhizae, monocropping of Bean + Mycorrhizae, monocropping of Bean + Bacteria, intercropping + Mycorrhizae, intercropping + Bacteria intercropping + Mycorrhizae + Bacteria. The results showed that significant differences (P≤0.01) in traits of bean such as seed yield, biological yield, 100 seed weight, and harvest index. Also traits of maize seed yield maize, biological yield, 100 seed weight and harvest index was significant (P≤0.05). The highest seed yield of bean (3053.7 kg/ ha) was obtained in the monocropping with bacteria and the lowest seed yield of bean of (1900.5 kg/ ha) was obtained in bean monocropping treatment. Also regarding to maize seed yield, maximum yield was observed (5751.9 kg/ha) in intercropping treatment with presence of bacteria, and minimum yield (2695.9 kg/ha) was obtained in maize monocropping treatment. The highes LER (2.89) was obtained from intercropping treatment without fungi and bacteria and the lowest LER (1.87) was obtained in treatment of intercropping system with bacteria. In general the results can be expected with a proper combination of biology fertilizers and intercropping system could improve biological nitrogen fixation and nutrient uptake.Finally as a result of this research could be mentioned that the best combination of treatments was intercropping system with mesorihzobium bacteria.