The invention relates to a method for calculating sensitivity of wind power plant reactive power on voltage based on a perturbation method and belongs to the technical field of automatic voltage control of a power system. The method comprises the following steps of: identifying the equivalent impedance of an external power grid accessing to the wind power plant according to the sensitivity of reactive power at a wind power plant grid-connected point on the voltage of the wind power plant through the perturbation method, and forming a complete power network together with a power network in the wind power plant; combining real-time measurement in the wind power plant to form a jacobian matrix, and calculating to obtain the sensitivity matrix of the reactive powers among the nodes in the wind power plant on the voltage; and finally, checking the calculation result by using the obtained sensitivity of the reactive power on the voltage through the perturbation method, if not, identifying the equivalent impedance of the external power grid again, and calculating the sensitivity matrix of the reactive power on the voltage until the sensitivity matrix passes the check. According to the method, the high-accuracy sensitivity matrix of the reactive power on the voltage is obtained finally and is used for voltage control in the wind power plant.