Aiming at the problem that the rock cutter load of cutter suction dredger in the construction process is difficult to quantitatively determined, we establish the tooth coordinate model, determine the tooth cutting condition according to the construction parameters, apply the load model of the single tooth cutting rock to build the overall load analysis model of cutter, calculate transverse force, vertical force, longitudinal force and power of the cutter under different rotational speed, the transverse velocity and attitude angle and thickness of mud conditions, and analyze each working with forward and reverse cutting of the cutter.The results show that the rotation speed and transverse movement speed of the cutter have a positive correlation with the power of the cutter, and the attitude of the cutter and the thickness of the mud layer have the greatest influence on the cutter load, no matter in forward or reverse construction.