Abstract: Objective TM satellite images from Poyang Lake region were applied to clearly identify the water body from other land surface.Methods The remote sensing data of Poyang lake region was collected.The color image composed by the layers of TM3,TM4 and TM5.The value of color image of dry and flood season was assigned to separate the water body from other of land surface.Results The values of pixels of water body were collected from dryseason image are focus on dle value of 2～5.9,11～11.9,38～41.9 and 45～45.9.In the flood season,the value of pixels was focus on 5～5.9,11～11.9,41～41.9 and 47～47.9.The area of water body of Poyang Lake was about 4357526400m² in dry season,and it was 5754122100m² in flood season.After the value of colorimage assigned,the water body was clearly identified from others in the image.Conclusion TM remote sensing image analysis would be a tool that can be used in the health ecological study.