Objective To compare biomechanical performance of four-part proximal humeral fractures fixed by novel locking plate or by AO-PHILOS plate. Methods The finite element fixation models of both the novel locking plate and AO-PHILOS plate for four-part proximal humeral fractures were established, respectively. The maximum Von Mises stress and displacement under 4 different functional positions of shoulder abduction in the two fixation models were compared by finite element analysis. Results The maximum displacement in shoulder abduction of 0°,30°,60°,90° were 6.644, 7.079, 5.850, 3.005 mm, respectively, in novel locking plate fixation model, and 6.293, 6.826, 5.774, 3.023 mm, respectively, in AO-PHILOS plate fixation model. Since the maximum displacements in both fracture fixation models were similar, it indicated that there was no significant difference in the stability for fixing proximal humeral fracture. The maximum Von Mises stress in shoulder abduction of 0°,30°,60°,90°were 1 033.0, 904.1, 888.1, 1 062.0 MPa in novel locking plate fixation model, while in AO-PHILOS plate fixation model, it showed 743.1, 692.4,486.4,393.5 MPa, respectively. During the process of shoulder abduction, the total stress in both fracture fixation models gradually decreased, but the new locking plate decreased in a larger range, showing an obvious stress dispersion. Conclusions Both the novel locking plate and AO-PHILOS plate can be used as internal fixation treatment for complex four-part proximal humeral fractures with no significant difference in stress distribution, and both showing a stable fixation effect. For fixing proximal humeral fractures with osteoporosis combined with the great and less tuberosity, the novel locking plate has an advantage over AO-PHILOS plate due to its unique anatomical wings and better fixing effect.