Abstract: The flow pattern and performance of fixed-geometry two-dimensional mixed-compression supersonic inlets with 90° configuration at the venter of the missile have been investigated by numerical simulation which has been validated by experimental data.Results indicate: 1) Under higher than started Mach number of 2.25 within range of suitable backpressure,the terminal shocks can be stabilized at the convergence channels of the inlet because the aerodynamic throat was formed by boundary layer.2) With the increase of the free stream Mach number,the total pressure recovery coefficient decreases,while the mass flow ratio ascends gradually and maintains 1.0 when the oblique shocks attach the cowl lip.3) With the range of the angle of attack to a certainty,the total pressure recovery coefficient and the flow ratio increase.But after the inlet is not started,with the increase of the angle of attack,the total pressure recovery coefficient and the mass flow ratio have been little influenced.4) With the increase of yaw angle,the total pressure recovery coefficient of the two inlets are all decrease.