The invention discloses high-precision penetration control laser plastic welding equipment and a working method thereof, and relates to the technical field of laser welding. The equipment comprises aframe body, a lower electrical cabinet and an upper computer, wherein a pressure closed loop clamping and pressing mechanism is fixedly mounted on the upper surface of a double-station turntable. Thepressure closed loop clamping and pressing mechanism comprises a mounting base, a centering and balancing stand column, a pressing cover plate, a bearing plate, a first precision electric cylinder, asliding table, a supporting column, a self-selecting model, a second precision electric cylinder and a numerical display welding penetration measuring ruler. A PLC control system man-machine interfaceconnected with the upper computer is arranged above the frame body. The method can reliably ensure finished-product consistency, can adaptively and actively perform adaptive welding speed and displacement exploration, pre-welding and penetration presetting on different types of workpieces to be machined, the diversity requirements of plastic laser welding are met better, the welding precision requirement is met better and traceability analysis and control functions are achieved.