Robots play an increasingly important role in the development of minimally invasive surgery (MIS). In MIS assistant robot systems, the remote center of motion (RCM) mechanism is a key component, and is the primary choice as end-effector for such systems. In this paper, first, we propose a new type of synthesis method for RCM mechanisms, which is based on the coupled motion of two DOFs to obtain new virtual center of motion (VCM) mechanisms, and then, through different combinations and configurations of VCM mechanisms, a new family of RCM mechanisms is achieved. Second, one of the obtained RCM mechanisms, which is deemed to have potential application prospects in MIS assistant robot, is investigated in detail, and a prototype is designed and fabricated to verify its feasibility. Finally, preliminary experiments are carried out on the prototype; the results show that, compared with existing ones, the new RCM mechanism's volume can be adjusted according to its required workspace, and it will be more compact when the required workspace is small. It will be an applicable option of end-effector for an MIS assistant robot.