For a long time, most of studies have focused on the aboveground terrestrial ecosystems, and underground ecosystems are poorly known until now. Nowadays, a growing number of ecologists are turning to study the underground ecosystems. Soil animals as an integral part of the ecosystem have attracted more attention of scientists. The underground trophic link is the most important connection of biological members in ecosystem. It is a key carrier of the material cycle and the energy flow. Therefore, the study of soil animal food web becomes a hotspot and frontier in the field of modern underground/soil ecology. Due to the particular properties of soil animals (such as small size, complex feeding habit and hidden habitat), it is difficult to study soil animal food webs in the field, thus choosing a suitable research method is quite important. This paper summarized the study methods in recent years and divided them into three categories: Traditional methods (direct observation, observation in culture experiments, and intestinal contents analysis), common methods (digestive enzyme analysis, fatty acid analysis, stable isotope techniques and compoundspecific isotope analysis), and modern molecular methods (DNAbased approach tracking trophic links and monoclonal antibody technology). With consideration of the properties of different soil fauna and advantages and disadvantages of each method, the methods of fatty acids and stable isotopes were applied more frequently; but with the improvement of molecular species identification technology and data accumulation, the DNAbased tracking approach will become mainstream in soil food web research.