First, UWPBL model(the university of washington planetary boundary layer model) is used to retrieve YaGi typhoon sea level pressure from sea surface wind data of SeaWinds which are obtained from QuikSCAT(called direct retrieving) and these strength results are analyzed. Then the variational method is used to decompose the sea surface winds field into two parts: vortex and irrotational environmental flow field, the UWPBL model is used again to retrieve YaGi typhoon sea level pressure from the vortex flow field, the results of typhoon central positions are analyzed by comparing the results with the results of direct retrieving, NCEP data and typhoon annual reports. It turns out that the accuracy of the typhoon sea level pressure central position is obviously improved. This method offers a new idea for the study of typhoon from microwave scatterometer data.