Abstract: This paper studies moderately under-expanded supersonicjet impinging on flat plate by using large-eddy simulation. A third-orderupwind compact difference and a fourth-order symmetric compact scheme areemployed to discretize the nondimensional axisymmetric compressibleFavre-filtered Navier-Stokes equations in space, while the third-orderRunge-Kutta method with the TVD property is adopted to deal with thetemporal discretization. The numerical results are first validated with theexperimental data of the classic impinging jet. The shock wave and vortexstructure with different scales in the flowfield, the wave traveling uponand reflecting back, and sound sources in different locations are acquiredin the simulation. The frequencies of the change of pressure and swirlingstrength in the shear layer at different position, pressure change on theimpinging plate, and the vortex merging in the jet shear layer are obtainedwith Fourier analysis. We found that the change of pressure and swirlingstrength in the shear layer, pressure change on the impinging plate, andvortex merging in the jet shear layer are associated with impinging tone.