Based on the simplex style of the traditional medical beds at home and abroad presently, a new folding mechanism of multifunctional medical bed was presented. After theoretical analysis, an optimal structure was selected. This mechanism consists of several planar four-bar linkages. It has one degree of freedom, which means it can be driven by only one driving torque to achieve multi-states changes. Therefore, it could save the space and reduce the weight of the bed as much as possible. The analysis of mechanism was carried out, simulation and stability were performed as well. A proto was established in the software named Automatic Dynamic Analysis of Mechanical Systems (ADAMS) to verify feasibility of the mechanism and the correctness of the design principle. It is an ingenious and brief design, which provides useful information for future research about folding medical bed.