Through experiments of corroded high strength steel bar specimens under cycling load, the effect of corrosion on mechanical property and energy dissipation capacity of high strength steel bar were analyzed. Based on test result, the degeneration model of mechanical property and energy dissipation capacity of corroded high strength steel bar was presented. It is revealed that the mechanical properties decrease gradually, the yielding plateau gradually shortens to disappear, ductility decreases, brittle fracture is even more apparent as corrosion rate of reinforcement increases; besides, under cycling load, hysteresis loop becomes narrow, energy dissipation capacity decreases gradually, which makes anti seismic performance of structure degenerate, and brittle failures can happen more easily in earthquakes.