The method of Endlich iteration and adjustment (ET method) for computing stream function and velocity potential in the limited area is used to computing the global stream function and velocity potential, which is compared with the method using the GaussSeidel iteration to solve the Poisson equations (GP method). The results show that the ET method is appropriate to compute global stream function and velocity potential, which makes the adjustment from inner to outer, i.e. using the value of the center grid to adjust that of surrounding grids. Therefore, the ET method does not need the exact boundary conditions, and eliminates the influence of the boundary on the results. The ET method can partition and reconstruct the original wind field with an accurate result. However, because of the influences of boundary conditions and difference schemes, the total of the rotational wind field and divergent wind field obtained by the GP method is different to the original wind field. In particular, when the meridional boundary has a constant value, the error between the reconstructed wind field and the original wind field is very obvious. Another important difference between the ET method and the GP method is that the former directly uses the partial differential equation between the stream function, velocity potential and wind field to make iteration and adjustment. It does not need to calculate the divergence and vorticity of the wind field, which not only guarantees the accurate reconstructed wind field, but also avoids the errors produced from the calculation of the divergence and vorticity.