Abstract: On the base of existing methods for computing the cable s prestressing force in design of anti-slide pile with prestressed cable, we consider the change of horizontal sliding force that acts on the anti-slide pile and suggest a method for computing the prestressing force. In the method, the cable, anti-slide pile, and the rock-soil surrounding the pile below the slip surface are regarded as a whole and the prestressing force should be calculated according to the long-time load, while the effect of the short-time load should be considered in the bearing capacity design of the cable and pile. The computation results show that the method leads the anti-slide pile and the cable to be at an advantageous internal force condition and hence to improve the structure s safety.