Aquarius is a satellite designed for measuring sea surface salinity (SSS). The Aquarius measurements may be influenced by marine environmental factors. The result is the inconsistency of data quality under different conditions. Although the data qualities have been considered in some previous studies, they have only been used for data screening. Base on this, a quality weighting method is proposed in this paper. The key differences between our method and traditional method, is way of weighting the data. In the present paper, both distance and data quality are considered in the weighting process. After the weight is determined, the weighted average fitting (WAF) method is used to calculate the grid SSS value. Then weekly 0.25°×0.25°gridded SSS fields between 40°S and 40°N are generated, covering the period from September 2011 through May 2015. The error statistics are calculated and the result shows that the root-mean squared difference (RMSD) is about 0.18 psu, which can improve the accuracy by about 31%. Therefore the method proposed in this paper could improve the precise of SSS filed with higher temporal and spatial resolution significantly.