Abstract: By running a tunnel test in Guangzhou, a continuous 48 h monitoring data for the concentration of pollutants (NO\-x, CO, SO\-2, PM\-\10\ and HC), traffic and meteorological data were obtained. The average motor vehicle emission factors of NO\-x, CO, SO\-2, PM\-\10\ and HC were then developed, which is 1.38, 15.40, 0.14, 0.64, 1.86 g/(km·vehicle) in sequence. The combined emission factors of 8 types of vehicle were also developed.