Abstract: In order to study the interaction between jet and supersonic flow, high accurate scheme was adopted to solve 2D Navier-Stokes equations studying the basic structure and law of interactions between jet and supersonic flow. The 5^th order WENO scheme and the 6^th order central difference scheme were used to discretize the convection term and viscous term respectively.Furthermore, the time marching scheme was adopted in the 3^rd order Runge-Kutta scheme, and the parallel computation was performed by using MPI non-blocking communication. Double backwards-facing step was presented in this paper. Supersonic flow (no jet), basic structure of jet and supersonic flow/jet interaction under different pressure ratios were studied respectively. It is found that jet structures with height above 20 km are highly under expanded jet. The interaction between supersonic slow and jet has obvious heating the wall of steps, which is about 400 K higher than that of the only flow. The complicated supersonic flow/jet interaction makes the flow field instability in advance, which forms the complex wave structure, shock wave/Kelvin-Helmholtz vortex interaction and other flow physics phenomenons.