Abstract: In order to study the certain relations between the species diversity and biology characteristics in vegetation restoration, in this paper, the abandoned croplands in Minqin oasis, the lower reaches of the Shiyang River were chosen as research object and the relationship between its biodiversity and soil enzyme activity was analyzed. The results showed that: (1) with the restoration continues, the species Margalef index, Simpson index and Shanon- wiener index showed decreasing trend, while the community dominance index first increased and then decreased; (2)influenced by salinization process in the abandoned lands, the contents of soil catalase was significantly higher than that of phosphatase, urease and invertase, the contents of phosphatase, catalase and invertase showed fluctuating increase trend with the abandoned cropland restoration, while the content of urease had a decreasing trend which maybe caused by the less material source and decreased biodiversity following cropland abandonment; (3) there was correlation between soil enzyme activity and biodiversity indexes, urease had the most significant correlation with the biodiversity indexes, followed by phosphatase, while catalase and invertase had weak correlation with the biodiversity indexes.