The invention provides a sliding bearing cooled and lubricated by gas-liquid phase fluid. The sliding bearing comprises an upper bearing seat, a lower bearing seat, and a top bearing shell and a bottom bearing shell, which are respectively installed in the upper bearing seat and the lower bearing seat, wherein a main lubrication oil inlet is arranged on the upper bearing seat, a main lubricating nozzle is installed at the main lubrication oil inlet, and a main lubrication oil outlet is arranged on the top bearing shell; and a main cooling gas inlet is arranged on the upper bearing seat, a main cooling nozzle is installed at the main cooling gas inlet, a main cooling gas outlet is arranged on the top bearing shell, and a cooling gas flow passage channel is arranged on the inner wall of the top bearing shell. Cooled by high-speed oil gas in a non-bearing area, the sliding bearing greatly improves the heat transfer capacity of the entire system, thereby greatly reducing the temperature rise value of the bearing. As high-speed air at the cooling nozzle contains low-speed lubrication oil, after being sprayed into the non-bearing area, the lubrication oil can adhere to a main shaft and is led into a bearing area by the high-speed rotating main shaft, thereby playing the role of oil supply.