In the present study, the MODIS data were used to monitor the situation of Ulva. prolifera in the Shandong Peninsula waters during the period of 2008—2012.Those studies mainly calculate the area of NDVI, and get the information of the time, area , scope , floating path of Ulva. prolifera by using threshold segmentation method. The feasibility of monitoring Ulva. prolifera information based on MODIS data and the macroscopic regularity of the outburst of Ulva. prolifera was elementally studied. The results showed that Ulva. prolifera first generated in the middle of May or early June, the time, area, scope of Ulva. prolifera reached a maximum, but the relative crowding density was earlier or later when Ulva. prolifera developed into a outburst. Finally, Ulva. prolifera died away after existing for 71 days in the late July or the early August. Wholly, the floating path moved to the northwest from off the coast to offshore. Based on those aspects above, the outburst of Ulva. prolifera in 2008 and 2009 was more serious than others.