A large number of spectral indices have been developed for estimation of leaf chlorophyll content. However, in most cases these indices have been tested for only one or at most a few related species, and thus it is not clear whether they can be applied across species with varying leaf structure characteristics. The main objective of the study is to find spectral bands that are sensitive to variation in chlorophyll content while relatively insensitive to species and leaf structure variation, determine optimal wide bands range for retrieving chlorophyll content of mixed canopies that consist of diverse species, and then develop wide-bands based approach to retrieve chlorophyll content of mixed canopies. We tested and compared 19 chlorophyll indices published on LOPEX93 (Leaf Optical Properties EXperiment 93) database to analyze the feasibility of using each of them as ’’universal’’ chlorophyll indices. Then the correlation between chlorophyll content and reflectance, the first derivative of reflectance spectra were studied based on LOPEX93 database, respectively. The results showed: (1) red edge spectral indices provided relatively good correlation with chlorophyll content when applied across a wide range of species; (2) the optimal band for estimation of chlorophyll content was found at 698-715nm range; (3) for the first derivative of reflectance, the optimal bands for estimation of chlorophyll content were at 720-735nm range and 535-550nm range. A, large number of spectral indices have been developed for estimation of leaf chlorophyll content. However, in most cases these indices have been tested for only one or at most a few related species, and thus it is not clear whether they can be applied across species The main objective of the study is to find spectral bands that are sensitive to variation in chlorophyll content while relatively insensitive to species and leaf structure variation, determine optimal wide bands range for retrieving chlorophyll content of mixed canopies that consist of diverse species, and then develop wide-band based approach to retrieve chlorophyll content of mixed canopies. We tested and compared 19 chlorophyll indices published on LOPEX 93 (Leaf Optical Properties EXperiment 93) database to analyze the feasibility of using each of them as ’’ universal ’chlorophyll indices. Then the correlation between chlorophyll content and reflectance, the first derivative of reflectance spectra were studied based on LOPEX93 database, respectively. The results showed: (1) red edge spectral indices provided relatively good correlation with chlorophyll content when applied across a wide range of species; (2) the optimal band for estimation of chlorophyll content was found at 698-715 nm range; (3) for the first derivative of reflectance, the optimal bands for estimation of chlorophyll content were at 720-735 nm range and 535-550 nm range.