The performances of a micro flexure pivot tilting pad gas bearing with the combined effect of rarefaction and the manufacturing defects were studied. A slip model derived from kinetic theory was used to simulate the flow behavior of the micro bearing. The gas film thickness equation was modeled to express the effects of microfabrication defects. The static, dynamic and nonlinear characteristics of the micro bearings were obtained by using the finite difference, perturbation and orbit simulation methods respectively. Results indicated that the slip flow and fabrication defects weakened bearing performance. A larger clearance depresses the effects of fabrication defects. A higher pad preload improve the bearing performance but make the bearing more sensitive to the manufacturing defects.