A method of slicing and printing colour 3D model is disclosed. The method includes following steps: loading a model data corresponding to a colour 3D model; adding a pollution-blocking structure next to the colour 3D model; executing a slicing process to the pollution-blocking structure and the colour 3D model for generating a plurality of pollution-blocking slices and a plurality of model slices and configuring colour each of the model slices; and, controlling a modeling nozzle (100) of a multi-colour 3D printer (1) to print the pollution-blocking slices and the model slices layer by layer and controlling a coloring nozzle (102) of the multi-colour 3D printer (1) to color each of the model slices.