The wing rock phenomenon induced by forebody asymmetric vortices is likely to oc-cur on modern aircrafts with slender forebody flying at large angles of attack.Over a model of a pointed ogive-cylindrical body with 30°swept wing at the fixed angles of attack in the wind-tun-nel,the effect of artificial perturbation’s location around the nose tip is studied through the free to roll test in the critical Reynolds numbers range.The test apparatus and test methods as well as data acquisition were presented too.The experiments are conducted in the 0.6m×0.6m section of transonic wind tunnel of CARDC.The encoder with the resolution of 0.088°which is coupled with the rotor is employed to record the free to roll motion.High precision mechanical bearings are used to minimize the friction in free to roll experiments.A spherical particle with the diameter of 0.2mm which is attached onto the rotatable tip of the model is as the artificial perturbation.Based on various type of experiments of forebody asymmetric vortices that influence the wing rock motion over the slender body with 30°swept regular wing,the relationships between tip perturbation and roll-ing oscillation induced by different types of forebody asymmetric vortices are studied.As the test result indicated,the manual perturbation on the nose tip could prevent the wing rock remarkably when it was placed on side direction and the control effect work on a wide range of attack and Mach numbers.The wing rock flow control mechanics are briefly analyzed too.