As friction pair, ZCuPb20Sn5 and No.45 steel are most in use in gear motor under oil lubrication. In order to investigate the tribological characteristics of ZCuPb20Sn5 and No.45 steel under emulsion lubrication, the authers tested them on MMW-1 friction and wear tester with sample pin and thrust ring. The relationships between the friction coefficient and the load, the friction coefficient and the speed, the wear rate and the load, the wear rate and the speed were provided. The worn surface of ZCuPb20Sn5 were investigated by means of scanning electron microscope. The results showed that, alone with the raising of the load and the speed, the wear rate of ZCuPb20Sn5 increased, but the friction coefficient reduced.