The planetary gear-bearing interference fit surface is prone to fretting slip under alternating torque, which can lead to fretting wear and fatigue failure. However, the current studies often ignore the influence of non-uniform interference on the stress and strain of the fit surface. In this paper, the force analysis of the planetary gear-bearing interference fit surface is carried out based on thick cylinders theory and planetary gear dynamics, and the fretting slip mechanism is explained in detail. Based on the assumption of plane stress, the equation for interference distribution in the circumferential direction of the fit surface is derived. On this basis, a three-dimensional fretting contact model considering non-uniform interference is established and solved by the conjugate gradient method (CGM). The results show that under the action of alternating torque, the fit surface interference is non-uniformly distributed in the circumferential direction, which shows a trend of increasing first and then decreasing. The fretting slip distance decreases first and then increases in the circumferential direction, but the fretting slip curve considering non-uniform interference shows a slip distance of nil in the range where the interference value exceeds the initial value. The model in this paper is more in line with the actual situation, and can provide more accurate theoretical calculation for the planetary gear-bearing interference fit design.