>In order to study spatial scale effect of lake water body extraction method based on remote sensing imagery,Landsat TM images are first upscaled to 100,250,500,1 000,2 000,3 000,4 000and 5 000m spatial resolutions from the initial 30mimage.Then Mixture Tuned Matched Filtering(MTMF)method is selected to conduct sub pixels unmixing and threshold method is applied to segment matched filtering score image to extract lake areas.Lastly,the spatial scale effect of remote sensing water body extraction is analyzed for different lakes with different sizes.The results lead to the following conclusions:①the nearest neighbor resampling method is proved to be more suitable than the pixel aggregate method for scale upscaling of remote sensing images with higher spatial resolution in spatial scale effect study on lake areas.② MTMF is a good choice for lake area extraction from remote sensing images at different spatial resolutions. But it is difficult to separate rivers or other water bodies from lakes.③The lake areas retrieved from upscaled remote sensing images vary with different spatial resolutions of these images.For one specific lake, the coarser the remote sensing image is,the larger overestimations of the lake area will be obtained,especially for lakes with small area.This work is very important for lake water body mapping with remote sensing at different spatial resolutions.It can not only provide useful information to understand the difference between lake areas retrieved from different remote sensing data,but also can help researchers to choose suitable reference data to validate their remote sensing lake areas.It would be very useful for remote sensing lake areas application in regional or global environment and climate change study.