The teleoperation master undertakes the important task of human-computer interaction and s the key equipment in the teleoperation system. Because the operator is susceptible to fatigue and other subjective factors, the risk of action errors during the operation is greater. In this paper, the trajectory constraint method of teleoperation assistant was studied, and the kinematics model of typical Omini teleoperation master hand was established. Combined with the principle of admittance control, a trajectory constraint method of teleoperation master hand based on virtual fixture was proposed, which reduces the risk of operator 's misoperation. A master experimental system including computer, Omini master hand and CHAI3D software is built to verify the effectiveness of the proposed trajectory constraint method.