This paper takes offshore sandbanks in Jiangsu Province as a typical study area.The reflectance of red and near infrared bands is sensitive to water depth based on the analysis of situ water depth and synchronously measuring water reflectance spectra.The linear correlation between depth and reflectance of Landsat TM1 and TM2 is-0.561 and-0.694 respectively.The water depth derived method based on the multispectral remote sensing transfer model shows that depth has linear relationship with the logarithm form of ratio of radiance（or reflectance） differences between deep water and two bands respectively

which are sensitive to water depth.TM4 and TM3 were found to be sensitive to water depth according to former analysis in this study and depth retrieval model was developed using reflectance of these two bands.The model（R2=0.4793） was tested to have good accuracy for depth less than 15m

whereas the predicted accuracy is unaccepted.The reflectance of TM5 combined with the spectra comparison between seawater and sand bank can be used to find the limit between seawater and other objects

which can be used to extract seawater in TM image.Then

water depth was computed by depth retrieval model in the study area.Fathom lines with 5m intervals can be detected through image managing software.With the development of high spatial

spectral and radiant resolution remote sensing technique

the research on shallow water bathymetry remote sensing method and its application will be under continuing investigation.