Based on the digital speckle correlation calculation and motion shaft surface matching method, a new method which uses dual cameras to measure dynamic torque of rotating shaft directly is put forward. Two industrial cameras are used to gather shaft surface image sequence which is used as reference images without torque, at both sides. Then surface strain images of rotating shaft under the action of torque are synchronously collected. Motion shaft surface matching method is used to search the corresponding reference images of strain images, and the full-pixel correlation calculation and the sub-pixel displacement calculation of gradient method are performed on two channels of strain and the reference images, respectively. The torsional angular displacement of both ends and the shaft torque are calculated. In order to verify measuring precision of the method, software Ansys is used to calculate torsional displacement of shaft. Compared with the proposed method, the error is 1.39% , which shows high consistency. Bench experiments under different rotational speeds and torque are done, and compared with standard sensor measurements, the error is 1.4% ~5.3%. Experimental results show that the torque measurement system based on digital industrial camera has high precision. The system structure is simple, and it overcomes the shortcomings of traditional methods, such as complexed installation, susceptible to interference. It is suitable for dynamic torque measurement of shaft.