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Coking industry is an important volatile organic compounds (VOCs) emission source in China,however,detailed information on VOCs emissions is lacking.Therefore,we selected a typical mechanized coking plant and collected air samples according to the Emission Standard of Pollutants for Coking Chemical Industry (GB16171-2012).Using gas chromatographymass spectrometry method,we analyzed the VOCs in the air samples,and applied maximum increment reactivity (MIR) rule to estimate ozone formation potential (OFP) of the VOCs emitted from the coke production.More than 90 VOCs species were detected from the coking plant,including alkanes,alkenes,alkynes,aromatic hydrocarbons,halogenated hydrocarbons and oxygenated VOCs.The concentrations ofVOCs (ρ(VOCs)) generated at different stages of the coking process are significantly different.ρ(VOCs) from coke oven chimney had the highest concentration (87.1 mg/m3),followed by coke pushing (4.0 mg/m3),coal charging (3.3 mg/m3) and coke oven tops (1.1 mg/m3).VOCs species emitted from the coke production processes were dominated by alkanes and alkenes,but the composition propotions were different at the different stages.Alkenes were the most abundant emission species in flue gases of the coke oven chimney accounting for up to 66％ of the total VOCs,while the VOCs emissions from coke pushing and coal charging were dominated by alkanes (36％ and 42％,respectively),and the alkanes and alkenes emitted from coke oven top were similar (31％ and 29％,respectively).Based on above results,reduction of VOCs emissions from coke oven chimney flue gases is suggested to be an effective measure,especially for alkenes.