The segment result for color image of blood cell by using the method of BP neural network approach on the platform of MATLAB is analuyzed, and the implementation of blood cell analysis and automation of count, improving efficiency, reducing operating error is realized. The comparison of different the segment results for color image of blood cell with BP neural and RGB threshold value method is given in this paper,and the conclusion that BP neural network is better than the RGB threshold is derived. The experiment in the case described here indicates that BP neural is strongly robust and has the property of high tolerant ability for difference color of different smeared.