A spatial color-mixing model based on tricolor angular frequencies is proposed in consideration that the design theory falls behind the application of digital camouflage pattern. The model is based on Fourier transform and Gaussian low-pass filter (LPF). In the model, the tricolor angular frequencies are introduced to the spatial frequency response function of human color vision, and the effects of atmospheric attenuation and air screen brightness on color mixture are considered. The field test shows that the model can simulate the color-mixing process in the aspects of color-mixing order, and shape and position of color-mixing spot. But the color-mixing spot color is not perfect, which can be improved by optimizing the atmospheric parameters and tricolor cut-off angular frequencies. The model provides a tool for the research on digital camouflage pattern.