Abstract: The compression-shear test method to measure the shear performance of Q345 low alloy steel + 304 stainless steel composite sheet with total thickness less than or equal to 10 mm was studied and compared with the conventional tensile-shear test method. The effect of overlap length on the test results of shear strength was also analyzed. The results show that the shear strength of the composite sheet could be measured by the compression-shear test method, and the repeatability deviation was less than or equal to 10 MPa. During compression-shear test which could avoid the shortcomings of the tensile-shear test method, there was no lateral peel force, so the test results could truly reflect the shear performance of Q345+304 composite sheet. With the increase of interface overlap length of compression-shear specimens, the measured shear strength decreased. Therefore, under the premise of meeting the standard requirements, specimens with small overlap length were preferred to carry out the compression-shear test.