To investigate the nonlinear seismic performance of partially concrete-filled steel bridge piers with thin-wall ribbed box sections during frequent and rare earthquakes, three test specimens, one not filled with concrete, one filled with concrete up to 20% of the height of a bridge pier, and one filled with concrete up to 40% of the height of a bridge pier, were produced and used in the pseudo-dynamic tests using the MTS servo loading system. The JRT-NS seismic wave, the same as that in the Hanshin Earthquake in Japan, was used in the tests, from which the displacement time history curve, load-displacement hysteretic curve, and cumulative energy dissipation time history curve were obtained. The experimental results show the following: all three specimens were in an elastic state under frequent earthquakes; under rare earthquakes, specimens filled with concrete at the base were in an elastoplastic state and showed good seismic performance, without the occurrence of significant destruction; with the increase of the filling ratio of concrete in the plastic-hinge region at the base, the constraint effect of concrete inside the thin-wall steel tube on the local buckling development of the tube gradually increased; and some seismic performance indexes, including the structural stiffness, horizontal bearing capacity, maximum displacement, residual displacement, and energy dissipation capacity of steel piers, were significantly improved.