It is difficult to apply some normal exploring technologies in areas covered by loess due to peculiar landform and geologic character. Oil and gas geochemical prospecting methods play an important role in these areas. But with the progress of the exploring extent, several oil and gas geochemical prospecting methods at present are not suitable for oil and gas exploration any more. Free hydrocarbons technology, one of the prevalent oil and gas geochemical prospecting technologies at home and abroad, is accepted widely for its effectiveness. Due to relief characteristics, this method is not used in loess areas. Wuxi Institute of Petroleum and Geology improved gathering tools, developed a portable device of free hydrocarbons gathering, and applied the device to areas filled by loess. The study received a good result.