Abstract: The soil interaction characteristics of geosynthetics are the key factors for geosynthetic reinforcement engineering, hence, it is essential to quantify the interaction by direct shear and pull out tests. This paper presents the results of a comprehensive investigation into the interaction characteristics (5 kinds of native geosynthetics with sand and lime fly ash) by direct shear and pull out tests. On the basis of the above mentioned results, some useful conclusions are obtained, which can be used to choose geosynthetic type and to make research on geosynthetic reinforcement mechanism.