Ultrasonic plastic welding indicates all thermoplastic materials that will be connected to each other in the welding seams. Under the interactions of force and energy, the longitudinal vibration and twisted welding in a frequency of 20kHz, 30kHz, 35kHz and 40kHz with an amplitude energy of 6 μm to 60 μm will be guided to plastic. The weldment and the mold structure will be welded together by ultrasonic vibration. People call these special structures in a weldment as an energy angle. Joining the direct contact angle between the surface profiles and thermoplastic parts can be focused to directionally deform by transferring high-frequency energy from a melting line. The materials will be melted by heat produced by friction of contact surface.