Abstract: The suction caisson foundation is an alternative foundation for cross-sea bridges. Based on the loading characteristics of the foundation of cross-sea bridges, a series of model tests are carried out to investigate the bearing performance of the suction caisson foundation. Different loading directions are considered in the model tests. The test results show that the vertical bearing capacity of the suction caisson foundation and the contribution of sidewall friction resistance increase with the increasing length of suction, and the tip resistance of caisson can be neglected. The lateral bearing capacity of the suction caisson foundation also increases with the increasing length of suction, but it is small and no more than 5 percent of the vertical bearing capacity. The lateral bearing capacity of the suction caisson foundation can be improved significantly by pre-applied vertical loading, and the bigger the pre-applied vertical loading, the greater the lateral bearing capacity. The factor should be considered in dealing with the large vertical loading in bridge engineering.