Benefiting from small incision and fast recovery, minimally invasive surgeries (MIS) exhibit great advantages in clinical operations. In such kind of surgeries, the remote center-of-motion (RCM) mechanisms play an important role owing to their special motion characteristics. This paper presents the design of a novel planar RCM mechanism of two rotational and one translational degrees-of-freedom. In the proposed design, the mobility of RCM mechanisms is decomposed into one-DOF pure rotation and translation with a remote stationary point. The dual-triangular linkage and the Peaucellier-Lipkin straight-line linkage are introduced to achieve the remote rotation and translation, respectively. Inspired by the concept of virtual screw, a dual-helical differential-motion joint is particularly designed to generate the coaxial rotation and translation. A preliminary prototype is developed to validate the feasibility of the designed RCM mechanism. The experimental results show that the developed prototype is easy to control and of acceptable positioning accuracy, which manifests potential application in MIS.