A method to monitor grassland vegetation health was used in this study.The relations of grassland bio-parameters related with grassland health were analyzed by Principal Component Analysis（PCA） on the basis of combining community survey and vegetation spectrum in Xilin River basin

Inner Mongolia.1.Three specific Principal Components（PCs） with specific ecological meaning were extracted from a 12-variables data set that contains community information using principal component analysis（PCA）.Based on the three PCs

we proposed a new index-GHI

which is proved to be qualified for monitoring grassland vegetation health condition

and sensitive to degradation.2.We extracted two PCs: visible light component and infrared light component from 6-band vegetation spectral reflection data.3.We got the regression models of GHI and visible light/infrared light

based on the PCs correlated to plot spectral reflection and GHI

which indicate community gross and grazing degradation.The model can be used to monitor grassland health condition by vegetation spectrum.