Scooter is the most popular personal vehicle in Taiwan; however, it also causes serious air pollution, especially in big crowded cities. In traditional method, vehicle exhaust emissions are measured with specific driving cycle in laboratory, but the test results hardly reflect the authentic exhaust emission for real world driving and road conditions. In the recently, OBS (On-Board Emission Measurement System) is a technology which can be installed on vehicles to collect exhaust emissions instantaneously on different road condition and time. This paper uses OBS (developed by ARTC, Automotive Research & Testing Center) installed on testing scooters to collect instantaneous exhaust emissions on typical roads and time periods. The test results can be used to analyze the scooter running characteristics of emissions.