The crackle color of Chinese date in full ripe stage are similar to the normal ones and not be readily detected., so a new method is put forward based on chrominance component for detecting crackle. Obtain respective color space images of cracked Chinese date; Cut out two images in the normal area and five images in the cracked area of chrominance components; Calculate luminance average value and luminancerange and standard square deviation to screen preliminarily parameters. The result is R in RGB color space and C in CMY color space; Do experiments with 108 Chinese dates including 78 crackled dates and 30 normal dates. The result show that R is superior to C. Use the adaptive threshold value method to draw a complete crackle including noise, adopt the median filtering method to eliminate tiny noise, employ regional labeling remove big noise to catch the right crackle. The correct recognition rate of crackled dates is 89.7% and the false positive rate is 3.3%, which can basically meet the accuracy requirement of Chinese red dates grading system.