The analysis on soil spectral data obtained from the different area of our country shows that exists a soil spectral line in 2-dimension space or multidimension space
but it is not a strictly straight line
it is a belt with certain width. It is not suitable for vegetation analysis with a united soil spectral line in the whole country. The influence of different soil spectral line on plant canopy and greenness assessment was discussed. In addition
the results and physical significance of the principal component analysis on the soil spectral reflectance were described.