The artificial blood smear examination is an important disease diagnostics of the patient's condition. However, because the sake of artificial coloring, digital image analysis of blood smear will be suffered by the un-uniform stain which is caused by (1) the procedure of making blood smear, (2) and the different dyeing agent. These situations mentioned above are the reasons that make the quality of image degeneration. In this paper, we present a simple method to ease the influence of un-uniform stain and extract the white blood cell nucleus for further analysis. Therefore, we can simply analyze the blood smear made by hand without using the scanner. Furthermore, we present a feature of lobes to distinguish the nucleus granulocyte (neutrophil, eosinophil, and basophil) from others. The experiment consist of 400 images of each kind of white blood cell to test the accuracy of this system we present.