Milk somatic cell image segmentation has a very important effect on milk quality analysis. In this paper, a new segmentation method is proposed for color milk somatic cell image. Aiming at the milk somatic cell image, a new method for image segmentation is proposed. First of all, selecting the appropriate color components by reducing the dimension of RGB color image; Then using the k-means algorithm to segment the low dimension image; Finally, the segmented images are fused by the region splitting and merging process. The experimental results show that the proposed method is better than the original three-dimensional (3D) color space segmentation method. The method improves in the performance and running time, the correct segmentation rate reached 98.4 %. Therefore, this method has certain feasibility.