By analyzing the impact of LSB replacing to the sum of RGB components of color image statistical properties,a new steganalytic approach for 24bit color images is proposed,which is based on the  frequencyrelated  sum of the RGB color components in a pixel. A classifier is constructed to identify the stegoimage from the normal images,which is based on the characteristics that the frequencyrelated  three color components’ sum of adjacent pixels is closer.The experimental results show that the proposed method outperforms the RQP steganalysis method in detection performance and in computation complexity.