Abstract: Odor pollution has been rated as the primary concern of environmental supervision. The monitoring of odor pollution by humans is being gradually replaced by instrument online-monitoring in order to implement a policy for urban grid management. However, the multi-compounds of malodorous gas as well as the cross interference restrict the development of odor online-monitoring. This paper introduces a malodorous gas online-monitoring technique based on the ultraviolet difference spectroscopic analysis and the verification of its metrological performance. This odor online-monitoring has a prospect of application in odor supervision in China because of its advantages, including high accuracy, low influence of cross interference and temperature as well as a reasonable price.