Abstract: In this paper,the data model and structure of soil information management system (SIMS) from the viewpoint of set theory are established. Considering the data of soil with orderless and uneven distribution both in space and time, the authors selected the relational module to be the data model of the system, this is favorable to the description of the data SIMS uses composed module structure, It is composed of data base subsystem module, management subsystem module and intelligence subsystem module. Based on the UNION operation,the set notations are:A = A1 UA2∪ -∪A6, B=B1∪B2∪…∪B5, C=C1∪C2∪…∪C5, C1=C11∪C12 ∪…∪C110,C4=C41∪C42∪…∪C414,SIMS=A∪B∪CRecord structure is adopted for the files of every data base except that of the soil nutrients, for which the record array structure is adopted. In order that the data be shared, the general table link structure is adopted to be the data structure of this system.