In order to understand the dynamics of soil water-stable aggregates and the relationship with soil nutrients on the land from the converting cropland into forest land project in the karst hilly area of Guizhou Province,4 kinds of the land with 5 to 8 years conversion age in the Zhongshan area of Liupanshui City were selected for a systematical study through the approach of substituting the temporal serial for spatial serial. In addition,the land of moderate rocky desertification and natural restoration pine samples were selected as controls. Results showed that the content of soil water-stable aggregates increased promptly in the forest stage years,and The water-stable aggregates were mainly in the range from 5 to 2 mm and there was an obvious tendency that water stable aggregates were in the transformation to a greater particle size. 0.25 mm aggregates were significantly correlated with soil organic carbon,total K,and quick acting K,but not with alkaline hydrolysis nitrogen and total P. It was necessary to keep soil organic carbon in a good balance in order to improve soil structure on the arable land in converting cropland into forest land project.