In order to monitor red tide in Case 2 waters, this paper proposes a method of multi normalized difference indices combination to extractred tide information from multi-spectral remote sensing image, and uses HJ-CCD and MODIS data to extract red tide information in the Shenzhen near-shore waters and the Pearl River Estuary to verify its feasibility. Because the spatial resolution of HJ-CCD is better than MODIS, the extract result is better than MODIS.