Aiming at the non-automatic problem of attitude measurement in monocular vision, an automatic measurement method for monocular visual attitude combining EPnP algorithm and SoftPOSIT algorithm is proposed. Firstly, the pose parameter of the stereo target is calculated by the EPnP algorithm, and the pose parameter is taken as the iteration initial value of the SoftPOSIT algorithm. Secondly, the iterative process of calculating the pose by SoftPOSIT algorithm is combined with the stereo target to realize the automatic measurement of the attitude, and the simulation verifies the validity of the topology to determine the pose. Finally, in order to verify the accuracy of the attitude measurement results, the stereo target is mounted on the two-dimensional turntable with the high-precision two-dimensional turntable as the reference, and the measurement data of the target pose is obtained by controlling the rotation angle of the turntable. The experimental results show that when the turntable rotates the angle from -20° to 20°, the standard deviation of the measurement results of the target attitude angle is 0.20°, and the standard deviation of the measurement results of the attitude angle is 0.27°.