Abstract: Based on a field test and FEM( finite elementmethod) numerical simulation, the load- bearingmechanism of the tunnelanchorage system ofsuspension bridgeswith pre-stressed anchor cable was investigated. The key parameters were determined through the back-analysis of the dynamic construction process. In the numerical simulation, interactions between anchorage and rockmass and between anchor cable, grout and rockmasswere simulated with zero-thickness contact elements. The research indicates that the initial pre-stress and free length of anchor cable determine the loads participated by anchor cable and anchorage on the tunnel anchorage system and their load-bearing occasion. There exists a least free length ofanchor cable to form a new confining pressure effect—rock anchoredwall to transfer and distribute stresses uniformly in rockmass.