Abstract: Some advanced aircrafts, especially those designed with using moderate aspect ratio, thin airfoil, trim, serrated, folding wings etc, are prone to encounter transonic abrupt-wing-stall, and furthermore bring out uncommanded lateral motion. To study the problem, due to the transonic abrupt wing stall, the free-to-roll test system was developed in the FL-3 Wind Tunnel. The static and free-to-roll wind tunnel tests for some aircraft models were conducted, including different configurations and different Mach number (0.8~0.95). The analysis used both the static and the dynamic wind test data to predict the abrupt wing stall sensitive range for the different configurations, and assess the corresponding severity of the uncommanded Lateral Motion. The characteristics of the uncommanded lateral motion caused by abrupt wing stall are predicted effectively at AVIC Aerodynamic Research Institute. The present study verifies the reliability of the testing facilities, establishes evaluation methods, and achieves transonic free-to-roll test technique.