Abstract: SUCROS crop growth model was rewritten into a modular model using VB programming language, and its calculation of water balance and function of crop coefficient were improved. With parameter calibration by crop field experimental data, the model may accurately simulate the major crop growth variables and yield. A regional crop growth simulation model, RCGM, was developed using ArcGIS Engine components by a tightly integrated method to combined GIS and simulation module, and it can be used to simulate crop growth and predict crop yield in a regional scale. The spatial database was established to manage spatial data for the regional model. RCGM was applied to simulate winter wheat growth and estimate crop yield at a county scale in Luancheng county, Hebei province. The simulating results were reliable with an average relative error of 12.51% between measured and estimated yields.