Abstract: This paper mainly dealed with the pyrenoid ultrastructure and gold immunolocalization of Ribulose 1,5-bisphosphate carboxylase(Rubisco)and Rubisco activase in chloroplast of several algae: Chlamydomonas reinhardtii, Chlorella spp. 640909, Enteromorpha clathrata that and Porphyra yezoensis. The results showed that there were different ultrastructure of pyrenoids among these different algae. Pyrenoid shaped in ball or ellipse, was composed by protein. The pyrenoid of Chlamydomonas reinhardtii, Chlorella, E. clathrata, was embedded by starch sheath, whereas the pyrenoid of Porphyra yezoensis had no starch sheath, and embedded by the thylakoids of chloroplast. The starch sheath was composed of starch, its side was related with the age and culture conditions of algae. There were channels in the middle of the pyrenoids, with which the pyrenoids connected the thylakoids of chloroplast. There was one portrait channel in the pyrenoid of Chlorella and E. clathrata, while there were several channels in the pyrenoids of Chlamydomonas reinharditt and Porphyra yezoensis. The results of gold immunolocalizatiopn showed the Rubisco and Rubisco activase distributed in the pyrenoid and starch sheath region. It was demonstrated that the pyrenoid had close relation with photosynthesis.