The invention discloses a coordination control method of VSC-HVDC (voltage source converter based high voltage direct current) alternating-current voltage-frequency for improving the transient stability of an alternating-current system. An alternating-current voltage-frequency coordination control target is increased in a transient state control target of a VSC station; the control strategy can be involved in transient state control of voltage and frequency of the alternating-current system by utilizing reactive and active rapid adjustment capability of VSC-HVDC respectively on the premise of guaranteeing the running safety of VSC-HVDC equipment. Based on the strategy, the invention designs a VSC controller structure capable of controlling the target priority ranking seriously, so that the transient state stability of voltage and frequency of a weak alternating-current power grid linked to the VSC can be improved effectively.