Bicycle is a typical unstable system.Although it is partly similar to the inverted pendulum systems, the complex mechanical characteristics cause that it is difficult to be analyzed and controlled.In this paper, Constrained Lagrangian method is used to building a rider-less bicycle dynamic model.Through the analysis of the dynamic model, the control system is designed to be divided into two parts: the forward control and the balance control.The rear wheel gets a stable speed by controlling the torque of the motor.Steering Angle Balance Control method is designed to keep the system balance.Use ADAMS to simulate a rider-less bicycle control system.The simulation shows that using Steering Angle Balance Control method can balance the bicycle to run forward and swerve stably.