Objective To compare the biomechanical stability of distal femoral fracture with metaphyseal comminution fixed by unilateral or bilateral locking plates. Methods Distal femoral fracture with metaphyseal comminution (AO type C2.3 fracture) models were established in 22 artificial femoral specimens, and randomly divided into single plate group (group A, n=11) and double-plate group (group B, n=11). In group A, the fractures were fixed by lateral anatomic locking plates, and in group B, the fractures were fixed by lateral anatomical locking plates at lateral side and straight locking plates medially, respectively. In each group, 5 specimens were applied with axial compression and 3 specimens were applied with cyclic axial loading to measure medial subsidence, and the remaining 3 specimens were applied with failure loading to record the maximum load to failure. Results For axial compression, the mean medial subsidence of group A and group B were (2.61±0.28) mm and (0.46±0.08) mm, respectively. For cyclic axial loading, the mean medial subsidence of group A and group B were (1.56±0.12) mm and (0.43±0.05) mm, respectively. For failure loading, the maximum loads to failure of group A and group B were (5 567±338) N and (9 147±186) N, respectively, which all showed significant differences in two groups (P＜0.05). Conclusions For fixing distal femoral fracture with metaphyseal comminution, bilateral locking plates show stronger resistance to medial compression than unilateral locking plates and thus increase the stability of medial column of distal femur, which contributes to patient rehabilitation at early stage.