The invention relates to a barrel-type damping device for a vegetable transplanter and a damping method of the device, and belongs to the technical field of agricultural machinery damping. The barrel-type damping device is mainly composed of a piston I, a brake arm, a friction plate, a hydraulic cylinder, a reset spring I, a protection spring, a damper barrel, a speed sensor, a hydraulic oil pump,a flow control valve and the like. According to the damping device, energy of mechanical vibration is converted into frictional heat energy of the friction plate on the brake arm and the inner barrelwall of a damper, and by means of the flow control valve, displacement of the piston in the hydraulic cylinder is precisely controlled, so that positive pressure between the friction plate and the inner barrel wall of the damper is changed, resistance is adjusted, and then precise control over counter-acting force of a piston rod is achieved; aiming at impact forces with different sizes, the damper gives corresponding counter-acting force so as to reduce vibration, and a better damping effect is achieved.