Abstract: In order to accurately calculate the emission of VOCs from oil storage processes, the factors affecting the emission of VOCs were quantitatively studied by using the method recommended in AP-42, a technical manual for compiling inventories of anthropogenic sources drafted by US Environment Protection Agency, taking gasoline as an example. The research showed that there were three kinds of important factors affecting VOCs emission: oil property parameters, oil storage state and meteorological parameters. Among various parameters, oil vapor pressure and the oil vapor molecular weight, tank sealing structure and tank condition, oil turnover times, ambient temperature and wind speed had great influences on VOCs emission. The VOCs emission increased exponentially with the increase of oil vapor pressure, tank diameter, oil storage height, ambient temperature and wind speed, and were linearly related to oil vapor molecular weight, oil turnover times and tank fouling factor. The influence of different sealing structures on VOCs emission could reach 2-3 times. On the basis of the research, the technical ways to control VOCs emission from the oil storage processes were put forward, in order to provide policy ideas for compilation of VOCs emission inventory and VOCs emission control in the process of oil storage, transportation and marketing in China.