To obtain the ultimate bearing capacity of suction caisson under inclined load in saturated sand, the interaction failure envelop was used to analyze the bearing behavior of suction caisson. Based on the 25 model tests in sand, the ultimate capacity of suction caisson under different loading conditions was summarized. The lateral capacity factor and the vertical capacity factor were assumed to analyze the influences of the loading position, loading inclination angle on the ultimate bearing capacity. It was found that there is a power function relationship between the normalized ultimate horizontal bearing capacity and the normalized ultimate vertical bearing capacity. Thus, the ultimate inclined bearing capacity can be obtained with the loading angle between the horizontal capacity and the vertical capacity.