Since the shear directly determines the displacement gradients of both out-of-plane and in-plane in the shearing speckle interferometry, the measurment precision of the shear should be improved to obtain the accurate strain distribution during the measurements of out-of-plane and in-plane strains. In this paper, four methods for the shear measurement: formula method,imaging method,Moiré fringe method and correlation method are compared in detail. An experimental setup is established to measure the shear using the imaging method, Moiré fringe and correlation method. The measurement results based on the three methods are compared with that of the formula method as a criterion. The result shows that when the shear is more than 3 mm, the correlation method has higher accuracy; however, once the shear is less than 3 mm, the Moiré fringe has higher accuracy. It suggests that the appropriate measurement method can be chosen after estimating the amount of the shear to obtain the higher out-of-plane and in-plane strains.