The invention relates to a pressure stabilizer and a liquid level measuring device. The liquid level measuring device comprises a first reference tube, a second reference tube, a water supplementing tube, a measuring connector and a pressure measuring device. The first reference tube and the second reference tube are erected in the pressure stabilizer. Water is supplemented into the first reference tube and the second reference tube through the water supplementing tube, and it is guaranteed that the liquid level in the first reference tube and the liquid level in the second reference tube arekept at first height and the second height respectively. Pressure generated from the liquid level positions in the first reference tube and the second reference tube to the height where the measuringconnector is located and pressure generated from the liquid level position in the pressure stabilizer to the height where the measuring connector is located are measured by the pressure measuring device through the measuring connector. By means of the liquid level measuring device, the influence of the temperature and pressure of a medium in the two reference tubes of a differential manometer is weakened structrurally, errors caused by the medium density and platform swinging are effectively eliminated, therefore, the precision of liquid level measuring signals is improved, normal operation ofa water level control system of the pressure stabilizer is ensured, and the safety and economical efficiency of a nuclear power plant are effectively improved.