To extract nuclei of white blood cell from the micro-image in visual field with microscope,a novel color image segmentation scheme using Support Vector Machines(SVM) is proposed.In this paper,the SVM is trained on 4097 positive samples made up of white blood cell nuclei pixels and 2910 negative samples(some red blood cells and background pixels).To improve the performance of real images,detailed analysis and comparisons are made by choosing different color spaces,kernel functions,samples.We demonstrate experimentally that the proposed algorithm achieves better performance than the existing methods,while being more rapid,accurate and robust.