Abstract: The vehicle emission has serious impact on the environment and human beings with rapid growth of motor vehicles quantity. This study used the domestic and foreign research achievements，with annual vehicle kilometers of travel，quantity of vehicles and emission factor，to calculate and analyze CO emission from vehicles in Xiamen. The results showed that the CO emission of vehicles was gradually decreased，but compared with the growth rate of motor vehicle population，the reducing speed was relatively slower. Under different emission standards，the same type vehicles CO emission from GBⅢ was the most，as 35%，followed by GBⅡ as 25%. When the emission standards were the same，light bus exhausted CO the most as more than 46%，and light truck followed as 34%. According to the result of predicting，effective precautionary measures can slow down the CO emission from vehicles.

Key words: motor vehicles, emission pollution, carbon monoxide emission