Abstract: The background wind field influence is evaluated with a new agorithm of synthetic aperture radar variational wind retrieval method that we put forward recently. Simulation results reveal that the first disadvantage of the direct inversion method is that when the background wind speed is high, the synthetic aperture radar normalized radar cross section is not sensitive to wind speed which leads to large wind speed errors. The second disadvantage is that when the background wind directions have errors, the normalized radar cross section will have larger errors, which will further result in larger wind speed errors. The variational method overcomes these two disadvantages. Forwardly, when the background wind speed is high, the variational wind speed errors are smaller than that of the direct method. But when the background wind direction is small, the direct wind speed errors are smaller than the variational wind speed errors. When the wind direction error of the background field is small, the wind speed error of the direct inversion method is smaller than that of the variational method.