Air foil thrust bearings are the critical components available on high-efficiency turbomachinery which need an ability to endure the large axial force. Air foil bearings are self-acting hydrodynamic bearings that use ambient air as their lubricant. Since the air is squeezed by the edge of compliance-surface of bearing, hydrodynamic force is generated. In this study, we measured the air film thickness and obtained the minimum film thickness experimentally. To increase the maximum load capacity, compliance of sub-structure was controlled. From numerical analyses, it is seen that, if the air film thickness is distributed more uniformly by variable compliance, the thrust bearings can take more axial load.