Purpose Little is known about how biomechanics governs the biological nature for humeral motion dynamically. Elbow motion ought to be investigated based on a musculoskeletal model and evidence the physiologic principle of upper limbs. Method A humeral model was reconstructed by MIMICS after CT images input in *.dicom format, it was processed by Geomagic Studio for Surfaces, then gridded mesh and assigned materials by Hypermesh. On the other hand, a musculoskeletal model was built by AnyBody, physical motions were then simulated to export boundary condition and myodynamia during flexion and extension. Finally, all the humeral model and boundary were imported to Abaqus for finite element analysis. Result During the simulative motion of flexion, the primary muscles are brachii biceps, brachialis anticus and teretipronator, their myodynamia increased and then decreased gradually, and reached its peak value at 30 degrees; During extension, the main muscles are triceps brachii and brachialis anticus, their myodynamia increased and then decreased gradually too, and reached peak at 50 degrees; In these two cases, their strain and displacement distributed at the middle of humerus. Conclusion AnyBody is a novel modelling system to simulate physical motion, for example flexion and extension. Biceps brachii and brachialis anticus are functional for flexion, and triceps brachii plays a key role in extension critically. This simulation confirms the physiologic rule for sport event, humeral fixation and postoperative healing with clinical significance that minimizing joint forces from injury onset may promote pain-free ways.