A detection method of chalky rice based on multi-peak distribution otsu algorithm is proposed.Firstly,the multi-peak distribution of the chalky rice gray imges is measured by mathematical and physical statistics.Then the gray levels of the chalky rice image are classified into three parts according to the chalky kernel features.Two segmentation thresholds are determined by the otsu algorithm,and the area of the chalky region is detected.Because the method of otsu can exactly segment different regions by using the gray-level histogram algorithm,the threshold of the chalky region can be adaptive.The experimental results indicate that the detection accuracy of the proposed method is 97.4%,which is better than the morphological watershed method.