An upwind local differential quadrature-Lagrange interpolation method to solve the Navier-Stokes equations for the flow field in the complex step flow was set up.The method to impose the essential boundary condition and the natural boundary condition was improved.The effect of support domain size

boundary condition treatment method and the upwind scheme on the accuracy of the calculation were analyzed.Calculation simulation shows that the high order Lagrange interpolation may cause numerical oscillation.The local differential quadrature method was recommended.The upwind support domain can improve the accuracy of the solution.Solution accuracy may be better in case of that the velocity support domain is lager than the pressure support domain.