Aiming at the underwater docking process of an autonomous underwater vehicle (AUV) and conical docking bay, this paper systematically analyzes the influence of docking geometry parameters and ocean current conditions on hydrodynamic characteristics. By establishing a three-dimensional mathematical model and using computational fluid dynamics (CFD) methods, this study focused on investigating the effects of the taper angle and diameter of the docking chamber inlet, as well as the magnitude and direction angle of ocean currents, on the docking resistance, lift, velocity field, and pressure field distribution of an AUV. The results show the following: increasing the dock inlet taper can reduce the AUV docking drag; the dock inlet diameter is positively correlated with the AUV docking drag; the larger the current speed is, the more drastic the change of the AUV drag is; the larger the current direction angle is, the larger the velocity difference between the upper and lower flow fields of the AUV is, leading to a significant lift effect. The research results provide a theoretical basis for the structure optimization and control strategy design of AUV underwater docking systems.