Objective To compare the biomechanical characteristics of new assembly of locking compression plate (NALCP) and locking compression plate (LCP) in internal fixation of femoral shaft comminuted fractures.Methods The preparation of a femoral shaft wedge fracture model (AO type 32-C2.1),six pairs of (12) femoral specimens were collected and divided into two groups randomly,with six in each group.The Group A was made up of the new assembly of locking compression plate fixation model (NALCP),and Group B the locking compression plate fixation model (LCP).The biomechanical properties of steel plates in two groups were tested by axial loading and torsional loading tests.The relative maximum displacement of fracture blocks in two groups on the X,Y and Z axes (the coronal axis was set as X axis,through the medial and lateral femur;the transverse axis was set as Z axis,through the femoral intercondylar fossa,perpendicular to the X axis;the sagittal axis was set as Y axis,perpendicular to the X and Z axis),the maximum strain,and the average strain of the steel plate were recorded.Strain distribution nephogram was produced,and the axial loading fatigue test results of Group A were recorded.Results Axial loading test:the relative maximum displacement of fracture in Group A on X,Y and Z axis were smaller than those in Group B (P ＜0.05 or 0.01);the main strain of Group A was greater than that of Group B (P ＜0.01);there was no significant difference in the average strain between Group A and Group B (P ＞ 0.05).Torsional loading test:The relative maximum displacement of fracture in Group A on X and Z axis was smaller than that of Group B (P ＜ 0.01);there was no statistically significant difference between the two groups on the Y axis (P ＞ 0.05);the main strain of plate in Group A was greater than that in Group B (P ＜ 0.01);there was no statistically significant difference in the average strain between Group A and Group B (P ＞ 0.05).There was no obvious difference in strain distribution between the two groups.In Group A,the fatigue test of axial cyclic loading was performed for 1 million times,and the NALCP was intact without deformation,loosening,or rupture.Conclusion NALCP can provide strong mechanical stability for comminuted femoral fracture.The design of bridge steel plate is reasonable,which can effectively avoid stress concentration,reduce the stress shielding of steel plate,and facilitate bone healing.