Precise cable drive has been developed as an alternative transmission element to gears, belts and pulleys, chains and sprockets in electro-optical tracking system. The analytical method is developed to predict the transmission backlash of precise cable drive to enable designers to better assess the precision performance in the design study phase. Slip angle of precise cable drive is studied, and the effect of the rotational velocity and inertia of cable on the force equilibrium of contact region is considered. The deformation of cable in slip region and free region is calculated respectively and theoretical formulation of transmission backlash for precise cable drive system is carried out. Parametric sensitivity is investigated to evaluate the relationship between the transmission backlash and precise cable drive parameters including preload tension, load tension, friction coefficient, center distance and output drum radius. Experimental setup is built and the transmission backlash is tested. Effect of preload tension on the transmission backlash is tested. Results show that the experimental value and the theoretical curve of the transmission backlash fit well, which validates the theoretical method developed in this article.