Abstract: Seven bands have been isolated from photo-membranes of N2-fixing blue-green alga Anabaena sp. 7120 using membrane solubilization and SDS-polyacrylamide gel electrophoresis methods.Five chlorophyll-protein complex zones with lowest eleetrophoretic mobility show the same characteristics of absorbance spectra and room temperature fluorescence spectra. They have a red absorbance maximum at 676 nm and a blue absorbance maximum at 438 nm. They exhibit a fluorescence emission maximum at 672—673 nm under room temperature; there are also three small peaks at 710, 732 and 740 nm respectively. These are characteristics of CPI chlorophyll. Therefore, we consider these chlorophyll-protein complex zones belong to photosystem I. Another chlorophyll-protein complex zone with intermediate mobility is termed complex II （CP Ⅱ）, with a red absorbance maximum at 672 nm and a blue absorbance maximum at 436 nm. Compared with CPI, both of the peaks shifted to shorter wavelength. It has a fluorescence emission maximum at 675 nm, and has not the smaller peaks characterizing of CPI. These properties show that this zone is different from CPI zones, and it is a complex associated with reaction center of photosystem Ⅱ.The zone of fastest mobility is free pigment.The fluorescence excitation spectra of CPI and CPⅡ at room temperature have been determined too.