Abstract: Abstract: Pig manure aerobic fermentation will produce a trace of volatile organic compounds (VOCs), although the VOCs content is less, but the effect on human health cannot be neglected. VOCs are not a single substance, but a class of compounds. In order to control VOCs, investigation of odor-causing matters of pig manures in aerobic fermentation was carried out in August, 2014 at the Key Laboratory of Energy Resource Utilization From Agriculture Waste，Ministry of Agriculture，Chinese Academy of Agricultural Engineering, Beijing, China. We set up the aerobic fermentation of pig manure and straw mix with water content of 65%, and the ratio of carbon to nitrogen 25:1. In the aerobic fermentation process, in every 30 minutes, there was a five-minutes ventilation, and the ventilation rate was 1.0 m3/(min·m3). Aerobic fermentation period was one month. We conducted an experiment to monitor volatile gas emission from the aerobic fermentation process, and determined the pig aerobic fermentation of VOCs components and their emission patterns. Research results showed that high temperature aerobic fermentation period lasted more than 10 days. It produced 33 kinds of volatile substances. Most of them emitted at the stages of high temperature. Besides ammonia and hydrogen sulfide, there were 31 kinds of VOCs, including benzene, toluene, ethylbenzene, ortho xylene, meta xylene and p-xylene, styrene, cumene, phenylpropane, mesitylene, tert-butylbenzene, pseudocumene, naphthalene, formaldehyde, acetaldehyde, acrylic aldehyde, crotonaldehyde, benzaldehyde, pentanal, hexaldehyde, methyl phenyl aldehyde, methanthiol, methyl sulfide, dimethyl disulfide, dimethyl trisulfide, 1,1-dichloroethane, sym-dichloroethane, trichloromethane, carbon tetrachloride, acetone, butanone and trimethylamine. Of these 31 VOCs, there were 12 aromatic hydrocarbons, eight aldehydes, four Mercaptan sulfur ethers, four halogenated hydrocarbons, two ketones and one amine. The correlation analysis between importance to smelly gases and odor concentration showed that methyl sulfide, dimethyl disulfide and dimethyl trisulfide were significantly positively correlated with odor concentration (P<0.01). Hydrogen sulfide and acetaldehyde were significantly positively correlated with odor concentration (P<0.05). So the smelly and odor-causing matters of pig manures' aerobic fermentation were mainly methyl disulfide, dimethyl sulfide, dimethyl trisulfide, acetaldehyde and hydrogen sulfide. In addition, dimethyl disulfide, dimethyl trisulfide, hydrogen sulfide and acetaldehyde were significantly positively correlated with methyl sulfide (P<0.05). In order to monitor the malodorous substances and provide reference for making control strategy in the aerobic fermentation of pig manure, we recommended methyl sulfide as a foul odor pollution indicator.