The invention provides a reactive power control method and a system of a new energy power station. The voltage of a network connection point is calculated according to the operation information of a local measurement and control device and the parameters of a network connection point tie line of the new energy station. When the voltage of the grid-connected point deviates from the voltage reference value, the reactive power adjustment amount of the new energy power station is calculated based on the voltage reference value of the grid-connected point and the voltage sensitivity of the grid-connected point with respect to the outlet of the new energy power station, and the reactive power output of the new energy power station is adjusted according to the reactive power adjustment amount. The scheme ensures that the reactive power limit value of the power station and the voltage limit value of the power station outlet play a fast reactive power regulation capacity to the maximum extent,so that the voltage of the grid connection point meets the reference value requirements, and the reactive power and voltage support capacity of the grid of the new energy power station is improved.