The invention discloses a built-in type liquid ring centrifugal pump without being filled with liquid. The built-in type liquid ring centrifugal pump without being filled with the liquid comprises a pump case, an impeller and a driving shaft, the pump case is provided with a liquid inlet pipe and a liquid outlet pipe, the impeller is mounted inside the pump case and drives the liquid to flow, one end of the driving shaft is connected with a driving motor, and the other end of the driving shaft is connected with the impeller. The impeller comprises a front cover plate, a back cover plate and spiral blades, the front cover plate and the back cover plate are fixed through side edge strips, and the spiral blades are arranged between the front cover plate and the back cover plate. An impeller inlet which is communicated with the liquid inlet pipe is formed in the center of the front cover plate, the impeller inlet is formed among the side edge strips, a liquid ring vacuum pump for drawing the air in the pump case is mounted on the driving shaft at the back side of the impeller, and a through hole which is communicated with the liquid ring vacuum pump is formed in the back cover plate. According to the built-in type liquid ring centrifugal pump without being filled with the liquid, extraction pipelines are of no need, a gas exhaust pipeline and a return pipeline are simplified, the size of the gas-liquid separation chamber of a self-absorption centrifugal pump is decreased, and the size and the weight of the centrifugal pump are decreased.