The invention relates to an electric steering gear system and a control method thereof, in particular to a multi-rudder cluster type electric steering gear system and a control method thereof. The multi-rudder cluster type electric steering gear system comprises a limiting part, an executing part, a sensing part and a control part, wherein the limiting part comprises an intermediate cross and an adapting body; the executing part comprises at least four motors, a plurality of gears and at least four output shafts; and the sensing part comprises at least four corner position sensors. By means of the limiting function of mounting holes of the output shafts, the positions of the intermediate cross, the output shafts and the adapting body are fixed. The corner position sensors are arranged in the inner cavity of the adapting body. Each corner position sensor is fixedly connected with corresponding output shafts through the output shaft mounting holes on the adapting body. Compared with theprior art, the invention has the advantages of small size, good manufacturability, strong anti-jamming capability and firm structure; moreover, each rudder can independently and flexibly rotate and perform accurate positioning.