The interaction flow with lateral jet in hypersonic flowfield was simulated numerically by solving three dimensional full N-S equations, using finite volume method, half implied Harten-TVD scheme and a algebraic Baldwin-Lomax model. The computation result was compared with the test data from foreign articles. The simulation captured the structures of shockwaves and eddies near the jet clearly, and showed the disturbed region to the missile. It proves that the jet has deep influence on the missile.