Machine vision system has a major role in making robotic assembly system autonomous. Part detection and identification of the correct part are important tasks which need to be carefully done by a vision system to initiate the process. This process consists of many sub-processes wherein, the image capturing, digitizing and enhancing, etc. do account for reconstructive the part for subsequent operations. Edge detection of the grabbed image, therefore, plays an important role in the entire image processing activity. Thus one needs to choose the correct tool for the process with respect to the given environment. In this paper the comparative study of edge detection algorithm with grasping the object in robot assembly system is presented. The proposed work is performed on the Matlab R2010a Simulink. This paper proposes four algorithms i.e. Canny’s, Robert, Prewitt and Sobel edge detection algorithm. An attempt has been made to find the best algorithm for the problem. It is found that Canny’s edge detection algorithm gives better result and minimum error for the intended task.