A device for transferring two-wheel motorbike into three-wheel vehicle includes a rectangle frame directly connected to the frame of the two-wheel motorbike and two side frames are connected to two ends of the rectangle frame. Two wing rods ARE connected to the two side frames respectively and an arm is pivotably connected to each of the side rods. A cushion means is connected between the side frame and the arm. A differential frame is connected between the two side frames so as to be connected with a differential which has an input end connected to an output shaft of an engine, and an output end of the differential is connected to two transmitting shafts which are connected to two rear wheels. The rear wheels each have a brake mechanism.