Plasma flow control,as a novel active flow control technique,has become a newly—rising focus of international aerodynamics and aerothermodynamics fields.PIV test investigations on flow characteristics induced by plasma aerodynamic actuation were done in the paper.The results showed that the flow induced by millisecond plasma aerodynamic actuation comes out as starting vortex and wall j et.The maximal velocity induced by millisecond discharge is about 5 m/s.The higher the voltage is,the stronger the starting vortex and the wall j et are.While the maximal velocity induced by nanosecond plasma aerodynamic actuation is about 0.5 m/s and the flow is similar to a shock wave upward.The discharge current for nanosecond discharge is 4 Awhich is much higher than that of millisecond discharge(O.1 A).So the nanosecond discharge results in a local fast heating due to high reduced electric field.The local heating caused pressure and temperature rise.The propagation of the pressure and heat induces shock wave and vortex which can enhance momentum and energy exchange between the boundary layer and inflow greatly.So nanosecond discharge is more effective than millisecond discharge in flow separation contr01.The results are instructional for increasing the ability of plasma flow control and can lay a foundation for the understanding of nanosecond discharge plasma flow control.