Abstract: Bionic flapping mechanism aims at realizing flapping motion of insect wings. It has become clear that two-degree-of-freedom flapping motion harmoniously is necessary for insects to produce enough lift. Double four-bar linkage mechanism and differential planetary gear train are two elements of bionic flapping mechanism, and its design, implementation, and testing were made. Driven by servo-actuator, double four-bar linkage mechanism transfers rotary motion to two sets of oscillating motions, then differential planetary gear train transfers oscillating motions to insectlike flapping motion of plunging and pitching. Mechanism kinematic analysis were made and linkage parameters and gear ratios were determined for implementing perfect flapping motion. Then instantaneous stroke angular position and angle of attack of the wing were plotted with respect to a complete alternation of upstroke and downstroke.