Soil vapor extraction (SVE) has been effectively used for the removal of volatile organic compounds (VOCs) from unsaturated soil in foreign countries. We have established a field site in a chemical plant in Beijing and carried out the remediation test of using SVE to remove the benzene. The effects of vacuum, vapor flow rate, soil air permeability and temperature on the SVE are studied. There is an optimal vacuum value at which the vapor flow rate is maximal. Both the pollutant concentration in the extracted vapor and decontamination rate of VOC increases with the increase of vapor flow rate and the latter linearly increases without considering the transport of VOC in the soil. The influence radius of SVE is larger and the vapor flow rate and decontamination rate are higher when the air permeability of soil is higher. The pollutant concentration in the extracted vapor and decontamination rate increases with the increase of temperature.