In clinical orthopedics or surgery, for the diagnosis of the forearm, elbow and wrist, X-ray radiography of lateral forearm is common. According to the current data, the relationship between the medial epicondyle and the lateral epicondyle of the humerus in the image is mostly considered to be completely superimposed. This experiment changes the distance between the central ray (CR) and the epicondyles of the humerus, then imaging and inspection separately. Experimental results show that in the lateral image of the forearm, the medial epicondyle and lateral epicondyle of the humerus do not superimpose, but they are clearly separated.