Abstract: The free-rolling measurement technique based on air bearing is an important method to measure small rolling aerodynamics of slightly asymmetric re-entry vehicle. In this paper, micro rolling moments of asymmetric-wing standard model were measured, and the air bearing was calibrated under windless or vacuum conditions. The effects of air-bearing dynamic characteristics, measurement error in original data acquisition, and parameter identification error were analyzed in allusion to characteristics of testing system. The results of comprehensive error and dominating error were identified for standard model test. The analysis results show the comprehensive errors of rolling moment coefficient and roll damping derivative approximate 10^-7 and 10^-4 respectively. There are different treatments of error in various tests. The research results have importantly practical significances to improving the accuracy, designing projects and instruments of free-rolling testing system based on air bearing.