Abstract: The significant wave height is an important parameter for characterizing the wave. With the development of remote sensing technology, satellite radar altimeter has become an important tool to obtain the significant wave height. However, those observations only covers the satellite ground track and cannot meet the needs of the application on large regions or areas. In this study, combined with the significant wave heights from HY-2 Radar Altimeter and the sea surface wind fields from HY-2 Microwave Scatterometer on October, 2013, a wind-wave relationship model for 0 to 40 m/s wind speed is proposed by using the regression analysis separately at high and low speed. By comparison with the other two wind-wave models, and validation with the satellite observations on November, 2013, it shows that it is credibility for wind-wave relationship model in the South China Sea based on HY-2 satellite observations, and especially, the model at low speeds has a good consistency with the wind-wave model from in-situ observations. Therefore, according to the wind-wave relationship model, the significant wave height can be computed from HY-2 microwave Scatterometer retrieved wind fields, and the data coverage, which is the same with the HY-2 microwave Scatterometer observations, is far higher than the satellite radar altimeter observations. It can and will provide more and useful wave information for the analysis or forecast of wind waves and storm surge disasters.