Abstract: The suction caisson foundation has been favored by many engineers due to its advantages such as wide size range, large ultimate water depth, good economy and convenient construction. However, the horizontal and vertical bearing capacities of suction caisson foundations are relatively low in soft clay. There is still no effective method to improve the bearing capacity of the suction caisson foundations. In order to effectively improve the bearing capacity of the suction caisson foundations, the mobile jet reinforcement technology and the form of rigid composite suction caisson foundation are innovatively proposed. The bearing characteristics of a suction caisson foundation reinforced by the mobile jet technology are studied through the model tests. The results shwo that the horizontal bearing capacity of the rigid composite suction caisson foundation is about 2.5~4.0 times higher than that of the ordinary caisson. The uplift bearing capacity of the rigid composite suction caisson foundation is about 3.5~5.0 times higher than that of the ordinary caisson. The propesed method increases the contact area between the pile and the soil and enhances the strength of the soil around the pile. The cement slurry evenly wraps around the caisson and the grouting effects are satisfactory. The jet parameters and soil characteristics need to be considered in the design of the new suction caisson foundation. It can provide reference for the engineering application of the mobile jet reinforcement technology and the theoretical analysis of the rigid composite suction caisson foundation.