Background:　White　Blood　Cell　(WBC)　image　segmentation　plays　a　key　role　in　cell　morphology　analysis.　However,　WBC　segmentation　is　still　a　challenging　task　due　to　the　diversity　of　WBCs　under　different　staining　conditions.　Objective:　In　this　paper,　we　propose　a　novel　WBC　segmentation　method　based　on　color　component　combination　and　contour　fitting　to　segment　WBC　images　accurately.　Methods:　Specifically,　the　proposed　method　first　uses　color　component　combination　and　image　thresholding　to　achieve　nucleus　segmentation,　then　uses　a　color　prior　to　remove　image　background,　and　extracts　the　initial　WBC　contour　via　Canny　edge　detection,　and　finally　judges　and　closes　the　unclosed　WBC　contour　by　contour　fitting.　Accordingly,　cytoplasm　segmentation　is　achieved　by　subtracting　the　nucleus　region　from　the　WBC　region.　Results:　Experimental　results　on　100　WBC　images　under　rapid　staining　condition　and　50　WBC　images　under　standard　staining　condition　showed　that　the　proposed　method　improved　segmentation　accuracy　of　white　blood　cells　under　rapid　and　standard　staining　conditions.　Conclusion:　The　proposed　color　component　combination　and　contour　fitting　is　effective　in　WBC　segmentation　task.