This paper mainly studied the relationship of the species biodiversity and the ground biomass at different desertification stages in Horqin sandy grassland in terms of species richness and function diversity.Correlative analysis suggested that the relationship of ground biomass and plant diversity was related to the basic unit of calculated biodiversity indices.Further research drew the following conclusions:(1)the function diversity,based on the life form classification of annuals,perennials and shrubs,had a close relationship with ground biomass at the fixed dune,semi-fixed dune and mobile dune stages.The correlative coefficients were-0.534,-0.574,and-0.431respectively.Functional diversity,based on the classification of legume,C₃ and C₄ plant species,had a good correlativity with the ground biomass at semi-fixed dune stage and the correlative coefficient was0.722.(2)The life form diversity had a negative relationship with ground biomass at the different desertification stages,which indicated that the lower evenness of life form composition of sandy land vegetation should increase ground biomass.(3)According to the species richness change traits of the different life form categories at the different desertification stages,the annuals had highest occupation frequency,perennials and shrubs in turn and the richness reached to9(±6.0),3(±2.6)and1.8(±1.0)respectively.Meanwhile,the average important values of life form showed that C₄ plant had the best fitness among C₄ ,C₃ and legume plant and the value were48(±12.3),39.7(±3.6)and12.3(±14.3)respectively.