Abstract: Offensive odour emissions from various storage tanks, wastewater treatment facilities and oxidative sweetening units of a typical refinery were monitored and evaluated comprehensively. The concentration of odorous gases, the emissions of total hydrocarbons, benzene homologues (BTEX) and odour were estimated. Results show that for the above mentioned odorous sources, pollutants in the emissions including NMHC, benzene, toluene, xylene, hydrogen sulfide, methyl mercaptan, ethyl mercaptan and dimethyl disulfide are over standard somewhat, and the over standard of concentration is more serious than that of emission rate. In this paper, odour pollutants and odour emission sources are classified into three classes based on their odour emission rates respectively. For odorous pollutants, class A is hydrogen sulfide, which occupies 67.9% of the total odour emissions; class B consists of methyl mercaptan, ethyl mercaptan and isopropyl mercaptan, dimethyl disulfide, methyl ethyl disulfide and diethyl disulfide, which takes 31.8%; class C is mainly BTEX, which only takes a 0.3%. For odour emission sources, sour water tanks are ascribed to class A, their emissions occupy 57.1% of the total odour emissions; wastewater treatment facilities, high temperature wax oil tanks and heavy waste oil tanks are belonged to class B and takes a share of 37.3%; alkaline sludge tanks, coke quenching water tanks, intermediate tanks and oxidative sweetening units are zoned to class C, their emissions take 5.6%. The emissions of total hydrocarbons from the main odour emission sources are 261 kg/h, in which the emissions from wastewater treatment facilities, sour water tanks and oxidative sweetening units account for two-thirds. The emissions of BTEX from the main odour emission sources are 23.8 kg/h, in which the emissions from wastewater treatment facilities and coke quenching water tanks account for two-thirds.