Investigations on the influence of different cavity structures on the reliability and cooling of thrust bearings were performed. Four cavity structure models were built. The variation laws of reliability and cooling characteristics of thrust bearing fluid domain under different structure and operating condition parameters were discussed. The influence mechanism was revealed. Four cavity structures were optimized for parameters. The results show that the high-pressure regions of the step and taper cavity structures are slender. Thrust bearings with step or taper cavity structure have better reliability and cooling. Thrust bearings with step-pocket or taper-pocket cavity structure can provide greater stiffness and damping, which effectively suppress the axial vibration of the rotor system. The depth of the cavity has the greatest effect on the load-bearing capacity of thrust bearings with different cavity structures. Through parameter optimization, the load-carrying capacities of four thrust bearings are increased by 19.23%, 37.44%, 30.60%, and 73.28%, respectively. The aforementioned investigations can offer theoretical guidance for the design and optimization of thrust bearings.