Abstract: The Pseudo-time Method and high accuracy rapid iterative scheme were developed for unsteady 3D N-S equations with unstructured grids.This scheme has two-order accuracy in time,and combines weighted ENO scheme (r=3) and strongly compact scheme to treat convection term in N-S equation and the right terms of the discrete equation.Besides,four-order accurate strongly compact scheme is used to calculate viscosity term of N-S equation.Three typical cases were used to check the scheme in different ways.Numerical test shows that the scheme not only has the character of high efficiency and high resolution,but also can keep high-order accuracy.Further,the computed results obtained from the proposed scheme are in good agreement with experiment and show the scheme can simulate physical process of unsteady flow with unstructured grids.