A control method of a permanent magnet generator, wherein the control method comprises: determining an active current reference initial value and a reactive current reference initial value of the permanent magnet generator in the current control period; searching, based on the active current reference initial value and the reactive current reference initial value, and with a target of maximizing a torque-current ratio in the current control period, an optimal active current reference value and an optimal reactive current reference value in the current control period; and controlling, based on the optimal active current reference value and the optimal reactive current reference value, the permanent magnet generator to operate; wherein the torque-current ratio is calculated based on a torque command value received by the permanent magnet generator from a wind turbine main controller and an output current value of the permanent magnet generator, characterized in that the searching, based on the active current reference initial value and the reactive current reference initial value, and with the target of maximizing the torque-current ratio in the current control period, the optimal active current reference value and the optimal reactive current reference value in the current control period comprises: searching, in the current control period, the optimal active current reference value and the optimal reactive current reference value on-line by using a hill-climbing method, or searching, in the current control period, the optimal active current reference value and the optimal reactive current reference value off-line by using a table lookup method; wherein a look-up table supporting an off-line search is obtained by performing an on-line search in advance, and the look-up table comprises optimal active current reference values and optimal reactive current reference values corresponding to different torques, rotational speeds and/or powers. determining an active current reference initial value and a reactive current reference initial value of the permanent magnet generator in the current control period; searching, based on the active current reference initial value and the reactive current reference initial value, and with a target of maximizing a torque-current ratio in the current control period, an optimal active current reference value and an optimal reactive current reference value in the current control period; and controlling, based on the optimal active current reference value and the optimal reactive current reference value, the permanent magnet generator to operate; wherein the torque-current ratio is calculated based on a torque command value received by the permanent magnet generator from a wind turbine main controller and an output current value of the permanent magnet generator, characterized in that the searching, based on the active current reference initial value and the reactive current reference initial value, and with the target of maximizing the torque-current ratio in the current control period, the optimal active current reference value and the optimal reactive current reference value in the current control period comprises: searching, in the current control period, the optimal active current reference value and the optimal reactive current reference value on-line by using a hill-climbing method, or searching, in the current control period, the optimal active current reference value and the optimal reactive current reference value off-line by using a table lookup method; wherein a look-up table supporting an off-line search is obtained by performing an on-line search in advance, and the look-up table comprises optimal active current reference values and optimal reactive current reference values corresponding to different torques, rotational speeds and/or powers. searching, in the current control period, the optimal active current reference value and the optimal reactive current reference value on-line by using a hill-climbing method, or searching, in the current control period, the optimal active current reference value and the optimal reactive current reference value off-line by using a table lookup method; wherein a look-up table supporting an off-line search is obtained by performing an on-line search in advance, and the look-up table comprises optimal active current reference values and optimal reactive current reference values corresponding to different torques, rotational speeds and/or powers.