Abstract:This paper concludes totally more than 600 species in 170 genera of sulfur-circulating prokaryotes, including more than 150 species in 48 genera with thium, more than 20 species in 6 genera belong to green sulfur bacteria, nearly 100 species in 33 genera belong to purple sulfur bacteria, 56 species in 23 genera with sulfur, more than 210 species in 50 genera with desulfurization (sulfate reduction), and 3 species and 1 genus with sulfur dismutation. According to the properties of these sulfur-circulating prokaryotes, they are classified as sulfur oxidation, sulfur reduction and sulfur dismutation and of vital importance to sulfur circulation in nature.