The traditional descriptions of soil and water loss are mostly the definite approaches based on the current equation(USLE).In fact,soil erosion is an indefinite complicated process influenced by various factors and complicated border conditions.This paper aimed to study how to use GeoCA to simulate soil and water loss in terms of its principles,forms and processes.Moreover,sustained by GIS,the study paid a great attention to the rules and the dynamic microprocesses from one state to another in order to form the GeoCA-Soil Erosion system using the Von Neumann neighbor.As an example,the system was applied in Wanzhou district,Chongqing City,and the relations of soil erosion with the basic factors were analyzed.Results show that urban soil and water loss in Wanzhou district has been effectively controlled,At the same time,the process can be visualized with the integration of GIS and CA technology.