The green tide occurred in the South Yellow Sea for 10 a from 2008 to 2017, affecting aquaculture, tourism and the safety of shipping in surrounding coastal cities. Studying the progress of the green tide and their influencing factors are of vital significance for understanding the distribution characteristics of the green tide in the South Yellow Sea and for preventing and controlling the green tide disaster. MODIS L1B data is used in this paper and normalized difference vegetation index is applied to extract related information of the green tide. According to the variation characteristics of the coverage area of the green tide, the whole progress of the green tide is divided into three stages: trigger stage, fast development stage and depletion stage. And the effects of sea surface temperature, precipitation and short-wave radiation on the variation of the green tide were analyzed. The results show that in the trigger stage, when the temperature is over 15℃, effective precipitation can stimulate the triggering of the green tide. The green tide can be detected by MODIS image within half a month following the effective precipitation. In the fast development stage, the sea surface temperature at the location of the green tide is 16–21℃, which is suitable for the rapid growth of the green tide. The solar short-wave radiation is concentrated in the range of 250～280 W/m², and the precipitation is important for the growth of the green tide during this stage. The peak coverage area of the green tide is low when precipitation is small, while the precipitation is extremely high in 2016 when the peak coverage area is the largest. During the depletion stage, the sea surface temperature rises to 22–26℃. When the green tide disappears, the average sea surface temperature exceeds 26℃, and the highest temperature reaches 27.48℃. The high sea surface temperature is one of the main factors for the demise of the green tide. The solar short-wave radiation is concentrated at 240–260 W/m², which is slightly lower than that in the fast development stage. The precipitation is relatively sufficient in this stage and no longer affects the growth of the green tide.