The approach for joining carbon fiber reinforced epoxy (CF/Epoxy) composites proposed in this study is based on the use of a plasticizing chip (PC), one side with rich resin and the other side with bare fiber, prepared by 1, 2, 3 or 4 pieces of glass fiber reinforced polyetherimide (GF/PEI) prepregs and a piece of glass fiber cloth (GFC), added as a last ply in the stacking sequence of CF/Epoxy composites. During curing, the epoxy partially penetrates in the side with a bare fiber of PC, leading to micro-mechanical interlocking as the main connection mechanism between the PC and the CF/Epoxy composites. To verify the effects of PC on the thermal and mechanical properties of CF/Epoxy composites, TGA, DMA, DCB, bending, interlaminar shear and drop-weight tests were carried out. The results showed that PC can effectively alleviate the impact of thermal degradation without weakening the properties of CF/Epoxy composites.