We analyse the detection and false-alarm probabilities of HCE-CFAR. The processing performance curves as functions of Y(the ratio of clutter level at two fields of the sliding window) are obtained respectively. Based on the performance companson between CA and HCE , the paper introduces a mixed form CFAR processing method and gives the process principle. Through the performance analysis and contrast.it is showed that the new method's synthetical perfomance is advantageous.