A torque measurement method based on digital industrial photogrammetry is proposed. Image signals of shaft surface before and after strain are collected by CCD industrial camera; and two-dimensional correlation calculation and sub-pixel displacement calculation based on gradient method are carried out on two images signals and strain displacement on surface of shaft is obtained

then the torque can be calculated. Experiment compared with resistance strain gauge method is designed

and error analysis are carried out. Experimental results show that torque measuring system based on the digital industrial photogrammetry has high precision

and the system structure is simple

it can be applied to small deformation displacement measurement of shaft surface.