With the advantages of low construction costs and rapid installation, suction caissons are widely used as foundations in offshore engineering. This paper investigates the behavior of suction caisson foundations located in sandy soil under horizontal cyclic loads. The upgraded simple anisotropic sand constitutive model with memory surface (SANISAND-MS model) is employed to accurately capture the sand's cyclic behavior. To calibrate the parameters of the upgraded SANISAND-MS model, a series of triaxial drained monotonic and cyclic tests was performed. The effects of load idealization and loading sequence on the cyclic behavior of sand are studied based on the element test results, and the effects of load idealization on the cyclic response of suction caissons are studied from a finite-element simulation perspective. The triaxial test results indicate that load idealization slightly affects strain accumulation in both loose and dense sand. Based on simulation results, it is found that the loading sequence of load packages with varying amplitudes has a minor effect on the rotation accumulation of the suction caisson. The current load idealization method used in the engineering design practice of suction caissons is acceptable under drained conditions.