In order to analyze the possibility of ultrasonic welding of wood-plastic composites, wood-flour(WF)/ polypropylene(PP) composite was ultrasonic welded, which contained 60%WF, 36%PP and 4% maleic anhydride grafted PP. The ultrasonic welding performance was evaluated by tensile tests and scanning electronic microscopy(SEM). The triangle energy direct stick was used in the ultrasonic welding. The results showed that WF/PP composite was successfully ultrasonic welded directly, while in the presence of energy direct stick, the strength of the welded joint was even better than the composite itself. It was concluded that the ultrasonic welding was suitable to WF/PP composites.