The utility model relates to a circular cooler of a compressor air inlet system. The circular cooler comprises a lower tray, wherein the middle part of the lower tray is provided with an air inlet passage, the cross section of the lower tray is in a U shape, the side wall of the lower tray is provided with a drain hole, the drain hole is in closed communication with a discharging valve, the upper surface of the lower tray is fixedly connected with an inner filter net and an outer filter net, both the inner filter net and the outer filter net are respectively of a cylindrical structure, the inner filter net is arranged inside the outer filter net, an internal space of the inner filter net is communicated with the air inlet passage, the side wall of the outer filter net is internally fixedly connected with a cooling copper pipe, the cooling copper pipe is arranged in a space between the inner filter net and the outer filter net, and the cooling copper pipe is connected with a compressor; the upper surface of the inner filter net and the upper surface of the outer filter net stay on the same horizontal plane, and the inner filter net and the outer filter net are collectively connected with an upper sealing cover in a cover way. Through the operation situation of the circular cooler, since the temperature of the air absorbed by the cooler is low, the exhaust temperature is greatly reduced.