Morphing aircraft is a new concept vehicle that changes its aerodynamic shape by a morphing mechanism to adapt to various flight environments and mission requirements, which has important application value in aerospace, military reconnoitre, and other fields and is the frontier and hot spot of future vehicle research. In response to the new development needs of wide airspace and wide speed domain of the morphing aircraft, a spanwise bending morphing wing mechanism with a multi-closed-loop space mechanism based on the equilateral Bennett mechanism was proposed. Firstly, the geometric characteristics of the equilateral Bennett mechanism were studied, and the design scheme of the multi-closed-loop morphing wing mechanism based on the equilateral Bennett mechanism was proposed. Secondly, the constrained spiral solution method was used to solve the degrees of freedom of the morphing wing mechanism, and the kinematic model was established based on the D-H coordinate transformation method. Then, the 3D model and virtual prototype of the mechanism were established, and the kinematic simulation was carried out to verify the above model. The prototype was made, and the experiment was carried out. The research results show that the proposed morphing wing mechanism needs only one power source to drive the mechanism movement, with a simple structure and high modularity rate, and the proposed morphing wing mechanism can realize the accurate connection between the parts and the expected spanwise bending action. The research results provide a reference for the basic research and engineering application of morphing wings for new types of morphing aircraft.