The invention discloses a coupler for a car. The coupler comprises a connecting shaft, conversion parts, connecting pieces, center holes, positioning holes, pins, driven shafts, buckles and driving shafts; the conversion parts are arranged on the left side and the right side of the connecting shaft, the driving shafts are arranged on the outer sides of the conversion parts, the buckles are arranged on the outer sides of the driving shafts, the driven shafts are arranged in the buckles, the pins are arranged at the two ends of each driven shaft, the connecting pieces are arranged on the front ends of the conversion parts, the center holes are formed in the center portions of the connecting pieces, and the positioning holes are formed in the end faces of the connecting pieces. The coupler iseasy and convenient to mount, safety is higher, machining cost is low, the mounting, dismounting and maintaining process is simple and convenient, the coupler can ensure higher centering of two shafts, transmission torque is large, buffering is ensured, vibration is reduced, during work, deforming or thermal expansion is not prone to happening, and therefore the occurrence probability of axial shifting and the like caused by reasons of deforming, or thermal expansion and the like during work is low.