Abstract: Supported by digital grid of 1∶50000 topographic map,quadratic polynomial and bilinear interpolation,the geometric calibration processing of TM image was made.By taking TM432 as the optimum band combination and using ERDAS remote sensing digital image processing system,the normalized difference vegetation indexes (NDVI) for Qingshui county in 1997 and in 2008 were calculated.Meanwhile,the profile and the difference chart of the vegetation index,together with the statistics were achieved.It was showed that compared to the vegetation index in 1997,that in 2008 is greatly improved and that the improvement rate takes up 13.4% of the total area of Qingshui.NDVI values of the whole county's 60% land all have the increment of different degree.

Key words: project of converting farmland into forest, TM image, NDVI profile, difference chart, statistic chart