Update publication information. Synechocystis sp. PCC 6803 is a model organism for study photosynthesis, energy metabolism, and environmental stress. It was the first fully sequenced phototrophic organism, but still nearly half of its proteome without functional annotation. In this study, we obtained 291 protein complexes, including 24092 PPIs among 2062 proteins by using co-fractionation and LC/MS/MS. From the protein network, we can learn more detail about how photosynthesis related to metabolism, cell motility, DNA repair, cell division, and other physiological processes. Meanwhile, the PPIs showed how protein function vary from bacterial to higher plant due to the protein interaction changed. It also allows us to uncover functions of hypothetical protein, such as Sll0445, Sll0446, Sll0447 participate in photosynthesis and cell motility, and Sll1334 regulates the expression of fatty acid. It is the most extensive protein interaction data in Synechocystis so far, which might provide critical insights into the fundamental molecular mechanism in Cyanobacterium.