A master-slave system with hydraulic actuated Stewart mechanism in both master and slave sites is built. The system can be used for curved surface grinding work, where the grinding dust may do great harm to the operator. Aiming at the 6-DOF work condition of the system, a new workspace-based four channel bilateral servo control algorithm is designed. The new algorithm may decrease the nonlinear disturbance such as the difference of the cylinders and environment force, thus improve the accuracy of the feedback force. Based on this result, a multi-DOF strategy switch algorithm is proposed. By using different control strategy under the rigid impact time and soft impact, the vibrate problem on the master side during rigid impact on the slave side is solved. An experiment including soft and rigid collisions is implemented to validate the efficiency of the new algorithm.