Abstract: With regard to the uplift bearing performance of suction-type cylinder foundations in non-homogeneous seabed foundation soils, this study introduces the linear gradient effect of undrained shear strength with depth, establishes the virtual work balance equation, and proposes an analytical solution for the overall shear damage mode of suction-type cylinder foundations. Comparison with model tests and some traditional theories verifies the reasonableness and validity of the derived upper limit solution formula for uplift bearing capacity, and further through parameter sensitivity studies, the influence laws of parameters such as soil nonuniformity and cylinder length-to-diameter ratio on the bearing capacity coefficient N_c are systematically revealed, and the influence effects of each factor are clarified by combining with the normalisation of the bearing capacity. The results show that there is a positive correlation between the upper limit solution F and each parameter, and the normalised bearing capacity coefficient N_c shows different trends with the change of the length-diameter ratio when the length-diameter ratio is changed by changing the radius of the suction cylinder only or changing the length of the suction cylinder only. The derived theoretical analytical formulas are closer to the results of the model tests than the traditional theory, indicating that the upper limit analytical formulas are reasonable within the error tolerance and have certain potential for engineering applications.