The invention discloses a method for measuring condenser pressure by using a differential pressure transmitter. The method can guarantee that the measured condenser pressure value is accurate, reliable and stable. The measurement process of the method comprises the following steps: measuring the condenser vacuum by using the differential pressure transmitter; connecting the negative pressure side of the differential pressure transmitter with a condenser vacuum measuring point and connecting the positive pressure side of the differential pressure transmitter with atmosphere; measuring the differential pressure value of atmospheric pressure and condenser pressure; then subtracting the differential pressure value from the measured atmospheric pressure value to obtain the condenser pressure; and setting the condenser pressure PK=Pb-PK', wherein Pb is the atmospheric pressure, kPa; and PK' is the differential pressure value measured by the differential pressure transmitter, i.e., the condenser vacuum value, kPa.