The design of master manipulators for master-slave surgical robotic systems is important because it may influence slave manipulator performance as well as the operator's workload. However, no design strategy has been presented thus far for optimizing the master manipulator design parameters. A master manipulator prototype and an experimental setup were developed for investigating design parameter influence using our master-slave microsurgical robotic system. The preliminary results showed that the relative position of the holding point, the corresponding point for the slave manipulator's working point, and the center of the gimbals are important for master manipulator design, especially for tasks requiring large or frequent posture changes. The experimental results also suggested that the optimized parameters would contribute to enhancing task efficiency and decreasing the workload, rather than increasing task accuracy.