In the date process of GPS control network in mining area,it shall be inevitable to treat the deformation of length projection,and this problem is more outstanding in high altitude region.In this paper,based on an actual GPS control network in mining area,the deformation of length projection is computed and analyzed,in which a compensation projection plane is selected to establish an independent coordinate system for mining area in order to restrict the deformation of length projection.After analyzing and discussing the solution for deformation of length projection,a basic approach to treat the deformation of length projection of control network for mining area in high altitude region is put forward.