The invention discloses a pneumatic hydraulic damping device of a turnover workbench. A bed body of the gas-liquid damping device is fixedly connected with a supporting seat, a rotation supporting shaft is fixed to the workbench, and the workbench is rotationally connected to the supporting seat through the rotation supporting shaft. A rotation seat is fixedly connected to a slide block of a linear guide rail pair arranged on the bed body. A pneumatic hydraulic cylinder is arranged on a guide rail seat, the rotation seat is connected with the end of a rod of the pneumatic hydraulic cylinder, one end of a connection rod is hinged to the rotation seat, and the other end of the connection rod is hinged to the workbench. The pneumatic hydraulic cylinder is connected with a pneumatic hydraulicdamping device body which provides hydraulic oil for the pneumatic hydraulic cylinder through a speed control valve and an oil pipe, the pneumatic hydraulic cylinder pushes the rotation seat to move,angle displacement of the workbench is generated through the connection rod, and the workbench is adjusted to stations of +90 degrees, -90 degrees and 0 degree through a limiting device. The hydraulicoil has incompressibility, the flowability of the hydraulic oil is lower than that of gas, thus, the stability of angle displacement of the workbench is ensured, the self-locking performance of the workbench after the workbench is turned over in place is also ensured, impaction is low when the workbench is switched between the stations, and the equipment stability and safety are high.