Abstract: Phenotypic characteristics of dairy cow is an important parameter to evaluate growth status of cows，in order to reduce excitability of cows and obtain geometric phenotypic size of cows easily，a phenotypic characteristics acquisition system based on depth image and point cloud data was designed by using image processing technology to extract phenotypic characteristic parameters of cows.Background subtraction，threshold segmentation，filtering and cavity filling were used to obtain target area of cows for depth image，and edge detection，corner detection，convex hull operation and other detection feature points were used for target.Finally，phenotypic characteristic size of cows was obtained from corresponding point cloud data.Field test of system was carried out and results showed that accuracy of body weight obtained was more than 98%，accuracy of body size was more than 96%，system had a high precision of measuring stability，which could lay a foundation for realization of digital breeding and has a good application prospect.