Image segmentation is important for target identification, watershed segmentation algorithm is widely used in image segmentation. In view of the over segmentation and sensitivity to noise problems of watershed segmentation algorithm, a image segmentation algorithm was proposed based on improved watershed algorithm. Firstly K-means clustering algorithm was used for the initial clustering segmentation, and then the watershed algorithm was used in image segmentation. The experimental results shows that the proposed algorithm has effect on solving the over-segmentation problem of watershed algorithm, And the image target is effectively segmented.