The invention discloses a supporting damping control system. The supporting damping control system comprises a supporting control valve and two or more supporting hydraulic cylinders. Hydraulic fluid flowing through the supporting control valve is connected or cut off in working cavities of all the supporting hydraulic cylinders. The invention further discloses a supporting damping control method. By means of a hydraulic steering supporting damping control system and method adopting the supporting damping control system, the hydraulic fluid is connected or cut off in the working cavities of all the supporting hydraulic cylinders, and the damping effect of a car body in a driving state and the car body stability in an operation state can be effectively improved; hydraulic main flow of an original steering control system is used, so that two switching ports do not need to be additionally arranged on a central rotary head, the height and the shape of the central rotary head remain unchanged, and an oil circuit reciprocating between the two additionally arranged switching ports can further be omitted; and an existing hydraulic control system is reasonably configured within a limited installation position and a limited installation space and is used for providing hydraulic supporting damping for the car body, so that the comfort and the safety of driving, working and other states are improved.