Pure cytoplasmic, thylakoid membranes and cell walls which were contaminated by thylakoid of the filamentous cyanobacteria Anabaena 7120 and its oxygen-sensitive mutant Anabaena-1 were isolated by mechanical disruption of the vegetative cells followed by discontinuous sucrose density gradient centrifugation. Pure cell walls were obtained from crude membranes by extraction with 2% Ttiton X-100. The prepared cytoplasmic membrane had spectral absorption at 455, 482, 519 and 673nm. Its SDS-PAGE map showed more than 30 polypeptide bands, among which there were three major bands which had molecular weight of 48, 55 and 104KD. The prepared thylakoid membrane had spectral absorption at 419, 438, 490 and 679nm. Its SDS-PAGE map showed more than 40 polypeptide bands, among them there was one major band of 54KD. The SDS-PAGE map of the cytoplasmic soluble fraction had more than 30 polypeptide bands, the amount of phycobitiproteins was the most of them. The SDS-PAGE map of the Triton-insoluble cell wall showed more than 40 polypeptide bands. The major polypeptide band(52KD) was mosaic protein and associated with the peptidoglycan non-covalently. Most of the proteins of the cell wall was sensitive to trypsin. The polypeptide of 52KD and 14KD were glycoproteins. No "heat-modifiable protein" was discovered on the cell walls of these two filamentous algae. This article compared the characteristics of the cytoplasmic, thylakoid membranes and the cell walls of the filamentous and unicellular algae. The differences of some physiological characters and characteristics of cytoplasmic, thylakoid membranes, cell walls between the wild type Anabaena7120 and the mutant Anabaena-1 were also discussed here.