In this day, people who become livestock farmers that workload is big are decreasing. When the cow especially acts the calving behavior, livestock farmers need to watch it for a long time. Therefore, the research is aimed for developing cow calving monitoring system to reduce burden of livestock. In the cow calving monitoring system, cow detection and extraction play a vital role. In this paper, the cow detection and extraction are focused on. In order to implement it, image obtained from video camera was analyzed and identified by using techniques of image processing. In the paper, black-haired cows from video sequences are detected and extracted based on inter-frame difference method and contrast rate features. Sobel edge detector and morphological operation are employed to complete results. The experimental results show strong points and weak points of the system.