Multi-walled carbon nanotube (MWNT) was filled into poly (ethylene terephthalate) (PET) matrix and MWNT/PET composite was prepared by injection molding process. The microstructure and electrical conductive property were investigated carefully. After injection molding, the electrical conductivity of injected sample decreased sharply because of the orientation of CNT due to strong shearing force. The electrical conductive network of CNT had been destroyed after orientation of CNT. Because of the difference of shearing rate between the surface and the body center during the injection molding process, a skin-core structure emerged. Near the surface, the injected sample has higher degree of orientation of CNT and higher electrical resistance.