The invention discloses an aerogenerator current transformer and a control method thereof. The aerogenerator current transformer comprises a grid-connected contactor, a precharge circuit, a current transformer, a network-side reactor and a machine-side reactor. The precharge circuit comprises a precharge contactor and a current-limiting resistor, and the current transformer comprises a network-side current transformer, a DC bus and a machine-side current transformer. The inlet wire end of the grid-connected contactor is connected with a power network, the other end of the grid-connected contactor is divided into two wiring ends, one wiring end is connected with the stator side of a generator, and the other wiring end is connected with the network-side current transformer through the network-side reactor. The network-side current transformer and the machine-side current transformer share the DC bus, and the machine-side current transformer is connected with the rotor side of the generator through the machine-side reactor. The precharge circuit draws power from the power network, passes through the precharge contactor and then is connected with the DC bus through the current-limiting resistor. According to the invention, through optimizing a blower fan whole-machine system main circuit topology structure, under the condition that the blower fan performance is not affected, switch devices are reduced, and the equipment cost and the labor cost are decreased.