Torsional buckling and failure of carbon fiber/epoxy resin composite thin-walled tubes (CTWTs) were tested and analyzed, and the effects of torsional buckling on the material failure and failure loads were simulated by finite element method. In order to enhance the torsional bearing capacity of CTWTs, the buckling/failure of the tubes filled with polymer foam were further simulated by ABAQUS. Numerous simulation results show that the buckling of the tube is strongly inhibited by foam core under torque. Because of the usage of crushable foam material, the influence of the elastic modulus and yield strength of the foam materials on the torsional failure modes and loads are studied. With the elastic modulus and the yield strength increasing, the buckling/failure load of CTWTs gradually increases and reaches the ultimate permitted strength of materials. Reasonable selection of the core material can help to obtain higher bearing capacity, and make full use of the high strength properties of composite materials.