Abstract: In order to solve the dynamic sealing of the panoramic electro-optical aiming device, through analysis of three typical kinds sealing principle of the panoramic electro-optical aiming device, the influence of friction torque of dynamic sealing on structure and accuracy of stabilized platform was analyzed. Combining with application of engineering practice, three kinds of sealing corresponding to the friction torque analysis and estimation methods were given, in order to help the follow-stabilized platform system design. Experiments of three kinds of dynamic sealing were analyzed and calculated respectively. Results indicate that magnetic fluid is the better way to solve the problem of dynamic sealing of electro-optical devices.