The vibration disturbance generated by Control Moment Gyro (CMG) has adverse effects on precision and stability of the attitude control system in spacecraft and there is still lack of effective methods to conduct mathematic modeling and analysis on it. Due that there is large structure difference between high-speed rotors and low-speed components of CMG, and it is hard to make mathematic modeling with unified methods, a system modeling method combined analytical modeling with test identification was established in the article to study the disturbance transmission mode of CMG, and an experiments was conducted to verify it. The results show that the disturbance transmission model proposed is correct and able to verify the conclusion that “unbalance vibration of high speed rotor is the main disturbance resource in CMG”.