Abstract: The differential settlement generated between the bridge deck and the approaching road willn be eliminated and bridge jump will also be prevented if geosynthetic-reinforced soil abutment is employed. To calculate its safety redundancy in the design, the ultimate bearing capacity of the geosynthetic-reinforced soil composite needs to be computed. Firstly, the model for calculating the ultimate bearing capacity of the geosynthetic-reinforced soil mass proposed by Wu and Pham is analyzed, and whether this model has the capability to predict the ultimate bearing capacity of geosynthetic-reinforced fine grained soil is questioned. To verify this problem, five geogrid-reinforced sand model tests and one unreinforced soil model test are then conducted under plain strain condition. The effects of reinforcement spacing and strength on the ultimate bearing capacity of the geosynthetic-reinforced soil are considered in the model tests. A comparison is made between the test results and those calculated using the model proposed by Wu and Pham. It is found out that the model proposed by Wu and Pham underestimates the ultimate bearing capacity of the geogrid-reinforced sand. Finally, a new analytical model is put forward based on the failure criterion of Mohr-Coulomb and the assumption of Rankine failure surface. The results calculated using the proposed model are coincident well with those obtained from the model tests.