The invention provides a rotor system and a control method of the rotor system as well as a gas turbine generator set and a control method of the gas turbine generator set. The rotor system comprisesa rotating shaft, a motor, a gas compressor and a turbine as well as a thrust bearing and at least two radical bearings, wherein a shaft body of the rotating shaft is of an integrated structure, the rotating shaft is vertically arranged, the motor, the gas compressor and the turbine are sequentially arranged on the rotating shaft, the thrust bearing and the radial bearings are arranged on the rotating shaft, the thrust bearing and the radial bearings are non-contact bearings, the thrust bearing is arranged at a preset position of one side, close to the gas compressor, of the turbine, and the preset position is the position where the center of gravity of the rotator system can be located between the two radial bearings which are spaced by the largest distance. According to the rotator system, the non-contact type bearings are adopted so that the rotor system can be vertically arranged; and in this way, the gravity center of the rotator system is located at the axis, static deflection cannot be generated, moreover, the torque generated by the gravity on the axis is zero, therefore, the influence of the gravity on the rotation of the rotator system can be eliminated, and then the stability of the rotator system can be improved.