CMYK mixed color FDM printer is a research and development project aimed at solving the problem that traditional monochrome 3D printing technology cannot achieve full-color printing and creating a 3D printer with reasonable price, easy to use, high precision and rich colors, so that more consumers can enjoy the fun of colorful 3D printing. Traditional 3D printing technology can usually only use monochromatic materials for printing, which leads to the color of 3D printed products is usually single, lacking realism and artistry. The goal of the desktop-level full-color 3D printer project is to create a 3D printer that can print with 4 color materials, so as to achieve more realistic and rich color effects of 3D printed products. This work mainly focuses on the key theory and technology of FDM full-color 3D printer color mixing. The new FDM technology 3D printing forming equipment independently developed adopts the principle of fused deposition molding, has a high degree of flexibility and precision, and can use a variety of colors. Printing materials, so as to realize full-color printing. It provides a certain practical significance for the development of more convenient, more efficient and low-cost full-color 3D printing equipment, and realizes more efficient printing.