Based on fdm3d printing technology, this paper designs a five in one out printing head for color 3D printing by using the principle of magenta yellow blue primary color matching. For 3D printing of melt deposition, the unreasonable thermal structure and distribution of the print head in the printing process will affect the accuracy of the whole printing process and the quality of the print. The thermal analysis method is used to optimize the structure of the five in one out printing head. The temperature distribution of the five in one out printing head in the printing process can be observed more intuitively. The rationality of the structure of the five in one out printing head is verified, which provides technical theoretical support for color 3D printing based on FDM.