The paper sets up an upwind local differential quadrature-Lagrange interpolation (DQ-Lagrange) method for solving the flow field in the interlocking labyrinth seal. The implementation of the Dirichlet boundary condition and the Neumann boundary condition is improved. The paper analyzes the influence of support domain size, the implementation of boundary condition and the upwind scheme on the accuracy of the calculation. Numerical simulation result shows that the high order Lagrange interpolation may cause numerical oscillation and the local differential quadrature method is recommended. The upwind support domain can improve the accuracy of the calculation. Solution accuracy may be better in case of that the velocity support domain is larger than the pressure support domain.