In view of the problems of motion stagnation and selfexcited vibration for the porous aerostatic thrust bearing used in the large supersmooth supportive stage for lunar orbit rendezvous and docking tests when going through the slot of air supportive stage,a theoretical model of the porous aerostatic thrust bearing was built according to gas lubrication theory,and the steady state characteristics of the bearing were studied.The dynamic timevariant characteristics when the bearing goes through the slot of air supportive stage were analyzed by the finite element method,and the variation of pressure distribution,carrying capacity and overturning moment were also analyzed.The results show that the existence of the slot of air supportive stage has a great influence on the pressure distribution of the porous aerostatic thrust bearing,which leads to the great reduction of the bearing capacity of the porous aerostatic thrust bearing in the process of cross slot,thus causing the bearing surface scratch.Therefore,more bearing allowance should be given in the design and selection of the bearing.The overturning moment of the porous aerostatic thrust bearing is fluctuated sinusoidally in the motion direction,but it will not affect the normal use of the porous aerostatic thrust bearing.