Abstract: Reserve estimation of the third kinds of minerals generally use traditional reserve，but the result of estimation in different methods are lager.In this paper，taking a limestone mine used in construction in Ningxia as an example.The model of recoverable mining area is established and the amount of resources is measured by AutoCAD software.The results are compared with those estimates of resources by using parallel section method，horizontal section method and horizontal projection geological block method.There is a discovery，error with parallel section method is the largest，horizontal projection geological block method is smaller，horizontal section method is the smallest.The research results show that The three methods can be used for the mine which has simple ore body.Generally，the parallel section method or horizontal projection method should adopted；the mine which has complex ore body should prefer horizontal section method.And should select appropriate level section according to ore body form varied.