A project named Chang'e is currently aiming to accomplish acquiring the lunar soil through automated robotic device. Therefore, many engineers are attempting to develop a kind of prototype of lunar soil coring for the mission. This paper presents a Rotary-percussive Drilling Mechanism (RPDM) which is a novel scheme for driving unit in the deep lunar soil sampling drill. The functions of RPDM behave in two aspects: rotation and percussion, and the two motions are individually driven respectively. According to the complex environments beneath lunar surface, RPDM can drive the coring auger and bit working in the following two modes: rotary mode and rotary-percussive mode. The detailed design of the RPDM is conducted and a prototype has been developed successfully. The mechanic analysis and dynamic simulation of the driving mechanism are implemented. The simulation results are consistent with results of the analysis.