An efficient fourth-order modified flux approach ENO scheme is developed to capture shocks and contact surfaces in unsteady compressible flows. No excessive additional computational time is required for the type of high-order ENO schemes. The numerical results show the high resolution of the scheme in one-dimensional scalar and the Euler equations. In two-dimensional simulations, the computed interferogram fringe distributions for a discharged shock wave are in good agreements with the experimental interferogram. The efficient and fast modified flux approach ENO scheme of the fourth-order is developed.