Abstract: Gracilaria lemaneiformis, an economical seaweed containing a lot of polysaccharide in the cell, was homogenized by means of the combination of the mechanical grinding and ultrasonic disruption, and then the thylakoid membrane was purified by the sucrose gradient centrifugation. The intrinsic chlorophyll-protein complexes with different pigment composition were isolated by the centrifugation after the purified thylakoid membrane had been fragmented with the non-ionic detergent, Triton X-100. Differential spectrophotometry of these isolated chlorophyll-protein complexes showed that the photosystemⅠwas obtained, and the photosystemⅡ was detected to have the activity of photo-reduction for DCIP. All these results indicated that the photosystem particles with activities can be obtained although the marine algal membranes are extremely resistant to attack by detergents.