In order to achieve opto-electronic system precision pointing, a structure of horizontal opto-electronic system, which was fixed on soft-rope hanged platform with attitude stabilizing device, was presented. According to the kinematics relationship of the parts of this system, some methods were employed to describe the topological configuration of the system, such as matrix of channel vector and matrix of constraint force element. Friction torque, platform attitude control torque and other disturbance torques were discussed. Lagrange method was used to establish the multi-body system dynamics model. Simulations were performed to study the influence caused by random rotation of the platform in the azimuth axis and pendulum in the plumb-horizon plane to the Line of Sight (LOS) pointing accuracies. It can be concluded that platform attitude controller is unnecessary when pointing controller is strong and the anti-twist system works well. Furthermore, pendulum would lead to coupling of azimuth angle and horizontal angle of LOS.