Abstract: Four type of in-water fluorometers were successfuly developed by authors in the past few years and applied widely to marine and river water mixing experiment; large or middle water area environment evaluation; trace oil in water and in situ marine phytoplankton chlorophyl a concentration measurment. In the dumping area of water in the Huanghai Sea and the East China Sea, we used the towing fluorometes are used, changing its fluorescence filter with neutral filter, for deep tracking measurment of suspended dumping material (coal ash, powder and alkali residue).It is first experiment in home and the experimeat results are satisfactory also. Fluorometry principle, advantage and underwater floor-ometer construction are described. Today, fluorimetry measuring in water material is a simple, quick, high sensitive and wide applicable measurment technique. It will plays the very important role in marine measurement in future.