Precision spacecraft has high demands on pointing accuracy; the flywheel is an integral part of satellite attitude control of the execution units, and in the development process, a small amount of eccentricity or dynamic imbalance comes into being, in the attitude maneuver and the process of control link, the rotation of the flywheel can cause interference force. Taking the imbalance mass as parts of a spacecraft, conducts the spacecraft attitude dynamic equations. And simulates the complete attitude dynamic equation, and according to the simulation result, simplifies and analysis the complete equation, and explains simulation results. It is found that when the flywheel is in high speed, static and dynamic unbalance mass have influence on the attitude, dynamic unbalance mass' effect on the attitude has small relation with the installation location, but there is a linear relationship between static unbalance's installation location and the attitude. When only single flywheel rotates, the pointing accuracy of the long-period depends only on the inherent characteristics of the flywheel, regardless of its speed. While multi-flywheels rotate, the attitude will oscillate or diverge, it relays on the initial phase; but the influence of the multi-flywheels rotating does not equal the summation of the influence of single-flywheel rotating.
