From 2005 to 2007, mixed community of white clover and bermudagrass were observed to investigate the above-ground biomass and inter-specific competition dynamics of the mix-sowed forage grasses. With the total density of the forage grasses unchanged, five seeding treatments were carried out, namely, treatment A (white clover, 100%), treatment B (white clover, 75%; bermudagrass, 25%), treatment C (white clover, 50%; bermudagrass, 50%), treatment D (white clover, 25%; bermudagrass, 75%) and treatment E (bermudagrass, 100%). The results indicated the aboveground biomass of the 3 mixture treatments (B , C and D ) were all higher than that of treatment A (2.078 kg/m2), but less than that of treatment E (4.406 kg/m2) in 2005 and the yields of 3 mixture treatments were all higher than that of treatments A and E in 2006 and 2007. The aboveground biomass of treatment C was the maximum (17.721 kg/m2) and was significantly different from other treatments (P<0.05) in 3 years. During the trial, white clover was the main grass in the early period of the each year. And in this period of time white clover and bermuda grass occupied different ecological niches and showed a symbiotic relationship with the competitive ability of white clover stronger than that of bermuda grass. Then, bermuda grass gradually became the main grass in all mixed grassland and the 2 forage grasses showed antagonistic action and the competitive ability of bermuda grass was stronger than that of white clover. At last, Bermuda grass became the dominant species of the mixed community.