Abstract: In this paper, a new type of geogrid structure named steel-plastic composite tenon geogrid is designed by attaching tenon to steel-plastic geogrid. Laboratory direct shear tests and pull-out tests between various typical backfills and geogrid and tenon geogrid are carried out respectively. The test results demonstrate that the tenon is useful to improve the mechanical characteristics between geogrid and backfills. Damage model between tenon geogrid and soils is analyzed. A simple theoretical formula describing the interaction shear strength is deduced. Comparisons between laboratory test results and theoretical results indicate that the friction angle based on the formula calculations coincides with that of the test results, although the cohesion is far different from the that of the test results. Based on the test results, the value of tenons contribution to cohesion is recommended to be 2 kPa to 7 kPa.