In order to investigate the role of Bacillus cogulans on yield of two forage corn cultivars, an experiment carried out at Agricultural Research Center of Tehran Province during 2009-2010. The experiment design consisted of three randomized complete blocks in a factorial arrangement. Investigated treatments consisted of the kind of phosphorus and cultivar. The phosphorus factor included of the application of triple super phosphate fertilizer and without seed inoculation, without fertilizer and without seed inoculation (control), seed inoculation and 100% P recommended, seed inoculation and 75% P recommended, seed inoculation and 50% P recommended, seed inoculation without fertilizer and cultivar factor included of S. C. 704 and 647. The application of 75% fertilizer and seed inoculation had the highest amount in the most of investigated characteristics. As regards forage quality, seed inoculation with %75 fertilizer showed the highest dry matter digestibility, crude protein and Water Soluble Carbohydrates, too. The present finding showed that phosphate-solubilizing microorganisms can improve crop yield.