The invention relates to a steam condensing type power station steam condenser chamber vacuumizing system which comprises a water ring vacuum pump unit, an air-liquid separator and a condensing water supplementing tank or a demineralized water tank contained with demineralized water. An air inlet of the water ring vacuum pump unit is connected with an air suction port of a steam condenser chamber, an air outlet of the water ring vacuum pump unit is connected with the input end of the air-liquid separator, the liquid output end of the air-liquid separator is connected with a liquid inlet of the water ring vacuum pump unit, and the output end of the condensing water supplementing tank or the demineralized water tank is also connected with the liquid inlet of the water ring vacuum pump unit. The system further comprises a first regulating valve for regulating the proportion of the liquid output amount of the air-liquid separator to the output amount of the condensing water supplementing tank or the demineralized water tank and then regulating working liquid to be at the optimal working temperature for the water ring vacuum pump unit, and the liquid output end of the air-liquid separator is connected with a hot well of the steam condenser chamber. The steam condensing type power station steam condenser chamber vacuumizing system is simple in structure, low in modification cost, small in maintenance work amount and capable of keeping a steam condenser to run under the optimal design pressure.