The invention discloses a feedforward-feedback composite control method and a control system for the pressure and the liquid level of a nuclear power station voltage stabilizer. A voltage stabilizer liquid level set value is recalculated; a new voltage stabilizer liquid level set value is only relevant to the average temperature set value of a loop cooling agent at current power and zero power; mismatched signals of primary loop reactor power and a secondary loop stream turbine power are taken as feedforward signals, and are introduced into a pressure and liquid level control system of the voltage stabilizer, thereby forming a feedforward-feedback consistency control scheme; the liquid level and the pressure of the voltage stabilizer can be subjected to corresponding compensation control in advance, so that the control effect of the voltage stabilizer is enhanced, the voltage stabilizer can reach a stable state more rapidly, and the stability of a pressurized water reactor nuclear power unit during frequency and peak load modulation is further enhanced.