series of acyclic and cyclic organic polysulfanes with three to six sulfur atoms are identified for the first time in petroleum (Ma3 well condensate) from the Tarim Basin, China. These organic polysulfanes are speculated to form through the nucleophilic addition reaction of hydrosulfide anion or polysulfides anions with low-molecular-weight aldehydes like formaldehyde in geochemical environment. The detection of these organic polysulfanes implies the incorporation of inorganic sulfur into organic matter during diagenesis, which helps to reconstruct the paleoenvironment and identify the oil source.