With the increasing complexity and diversity of 3D printed parts, the single-material parts can no longer meet various special performance requirements. Functionally graded material parts have gradually become a research hotspot in rapid prototyping manufacturing industry. In order to meet the manufacturing requirements of functionally graded material, a spatial mapping modeling method for functionally graded material based on coordinate transformation was proposed. The key of this method was to effectively combine geometry information with material information. Firstly, the material space of functionally graded material model was constructed by using the single gradient source method and multi-gradient source method. When the cross-gradient source model was encountered, the material distribution was calculated by using a specific intersection operator with a certain weight ratio. Then, in the process of combining the geometric space and the material space, the coordinate system of material space and geometric space was cleverly cooverlapped through coordinate transformation to realize the mapping of material space to geometric space, so as to obtain a functionally gradient material model with material information. The required functionally graded material model could be obtained by modifying the gradient source, material distribution function and coordinate transformation method. The results of visual analysis of the instance model through Visual Studio 2019 and OpenGL programming languages showed that the proposed modeling method greatly shortened the modeling time compared with most valuation modeling and non-valuation modeling methods, and fundamentally solved some problems of insufficient storage space and cumbersome modeling process caused by some algorithms. The spatial mapping modeling method for functional gradient material based on coordinate transformation can provide a new modeling method for the additive manufacturing industry and has good application value.