Abstract: The remote sensing image information capacity is a kind of evaluation model which be able to characterize the surface complexity，and its calculated value size is closely related to the number of image gray levels. Besides，remote sensing image information capacity is also sensitive to the change of image grey value. Vegetation is the main factor of surface cover，and different vegetation types have different gray values，thereby affecting the value of the [DN] of the image，so the fractional vegetation cover is the main factor of affecting the vegetation cover gray complexity. Information capacity is calculated based on image DN value image quality evaluation criteria that can accurately and effectively express gray structure information. Therefore changes in vegetation will affect the image information capacity，and vegetation index is an important factor in the study of vegetation in remote sensing. The paper selected 19 samples in the same period of the image to calculate the information capacity of these samples and a variety of vegetation index，in order to further research the coupling between information capacity and fractional vegetation cover. The paper mainly studies the fractional vegetation cover，[NDVI，][RVI] and other two vegetation indexes. At the same time，it also makes various correlation analyses among fractional vegetation cover，the mean and standard deviation of the five vegetation indexes and information capacity. The result of research shows that information capacity has less correlation with the mean of fractional vegetation cover and vegetation index and information capacity，but quite related to standard deviation. Among that，standard deviation serves the largest correlation with information capacity as that：R²=0.824 5. At the same time，the correlation analysis is made between standard deviation of fractional vegetation cover and information capacity，the maximum correlation coefficient between them is R²=0.864 2. Finally，the study not only shows that the remote sensing image information capacity has obvious correlation with these several types of vegetation indexes and fractional vegetation cover，but also can effectively characterize the changes of surface structure.

Key words: remote sensing imagery； information capacity； vegetation index； , fractional vegetation cover； , correlation analysis