We have acquired a total of 68 isomers of sulfur clusters S n (n=3-11) based on molecular graphics and then carried out optimizations and vibrational analysis by means of the B3LYP DFT method. Inside these structures, the sulfur atoms could be in one-fold, two-fold and/or three-fold coordination. According to total energies, the isomers have been ranked for stability. Many sulfur clusters are composed of atoms in two-fold mode. Compared to a S n structure with all atoms in two-fold mode, that with atom(s) in one-fold and three-fold coordinations is higher in energy. It seems that it is difficult for a sulfur cluster to form a cage structure with the involvement of three-fold atom(s)