The invention provides a self-resetting friction damper for a beam bridge seismic isolation system. The self-resetting friction damper comprises a damper cylinder, a friction device, a first elastic device, a second elastic device, a piston and a guide rod; the guide rod penetrates through the whole damper cylinder; the piston moves leftwards and rightwards along the guide rod and is respectively connected with the left wall and the right wall of the damper cylinder through the first elastic device and the second elastic device; the friction device is movably connected with the upper wall and the lower wall of the damper cylinder; the piston is connected with the friction device through a connecting oblique rod; a limiting device is arranged between the connecting oblique rod and the piston. The invention aims to provide the damper which has the energy-consuming capacity and a self-resetting function; the self-resetting friction damper has the frictional force to realize energy consumption when an upper structure deviates from an equilibrium position and has no frictional force in the process of returning to the equilibrium position, so that the resetting resistance is reduced; all the components of the damper are within an elastic scope in the whole process, so that a series of problems existing in the prior art are effectively solved.