Ocean front is a very important research object in ocean dynamics. At present, satellite remote sensing mainly uses sea surface temperature data to analyze the ocean front. However, due to the convergence of sea surface temperature in summer in China's offshore waters, the existence of the front is covered up, and the biooptical characteristics of different water masses are often different, and there is no significant seasonal variation cycle caused by the influence of solar radiation.Therefore, satellite sea color data can effectively make up for the deficiency of ocean front detection and improve the accuracy of ocean front detection. Based on Multi-source Satellite merging data, this paper uses gradient detection algorithm to study the ocean front in China's offshore waters. Combined with the seasonal transformation law of SST and blue-green band remote sensing reflectance ratio, this paper uses different gradient detection thresholds applicable in different seasons to obtain the distribution law of SST front and sea color front in China's offshore waters. A more comprehensive detection of China's offshore front can be realized through the complementarity of sea temperature front and sea color front.