Endurance tests of catalyst were conducted with the standard bench cycle (SBC) and standard road cycle (SRC). Emissions of different endurance mileages were also measured. In SBC test, CO emission kept unchanged, NOx emission obviously increased and THC emission had a small increase with the increase of endurance mileage. In addition, CO transient curve changed from single peak to double peaks with smaller peak value than that of single peak, NOx transient curve showed double peaks with the characteristics of first increasing peak and second constant peak, and THC transient curve displayed single peak of increasing trend. In the SRC test, CO and emissions increased and THC emission first increased and then decreased. In addition, CO transient curve showed a single peak of increasing, NOx curve showed double increasing peaks and THC showed single peak of first increasing and then decreasing.