Based on the theory and methods of geostatistics,by using computer,mathematic economic model packages software for ore deposit and Micromine's packages software,this paper establishes a three-dimensional deposit mathematical model for certain orebody of Dachang orefield in Guangxi province.The results show that it is easy to know the form,dimension and distributing characters of chemical composition of the orebody with this model,which provides foundation for bounding orebodies dynamically and calculating reserves.