Abstract: Study on the structure and control principles of the platform stabilizing control mechanism of the modulating rotary steerable drilling tool was conducted.A method of performing platform stabilization control was described by using the downhole turbine generator as the initiator of force moment and by adjusting its electromagnetic moment.Based on the derivation of the mathematical model of the controlled object,corresponding computer simulation was conducted on the control system.The results showed the feasibility and effectiveness of the controlling plan.