The invention relates to a VSC-HVDC power control method for improving voltage stability. For the voltage stability problem of an alternating and direct current hybrid power network containing VSC-HVDC, through consideration of constraint conditions such as VSC-HVDC capacity limitation, an alternating and direct current parallel series system VSC-HVDC active power and reactive power optimal calculation model based on voltage stability is established. Through solution of a Lagrange function, the VSC-HVDC optimal active power transmission capacity and reactive output and the maximum power supply load of the alternating and direct current parallel series system can be obtained. According to the method, through optimization of the VSC-HVDC active power and reactive output, the feasible method for improving the voltage stability is provided for the alternating and direct current hybrid system.