The role of the sulfur 3d orbitals in bond formation is discussed by taking into accountthe influence of the environment on the orbitals of the sulfur atom in the molecules. The ca cula-tion results of a series of prototype molecules containing sulfur such as SF_2, SF_4, NSF_3, SF_1, H_2Sare reported. It is convincingly shown that in highly electronegative environment the energy levelsof the sulfur 3d orbitals are reduced to the vicinity of those of the ligand valence orbitals and theirspatial distributions are contracted to the bonding area, and therefore they can participate in bondformation to a certain extent, which is enhanced by the formation of the d-p π back bonds. Itseems that the result reported in this paper is helpful for the solution of the long-standing debateabout the sulfur 3d orbital participation in bond formation. The role of the sulfur 3d orbitals in bond formation is discussed by taking into account the influence of the environment on the orbitals of the sulfur atom in the molecules. The ca cula-tion results of a series of prototype molecules containing sulfur such as SF_2, SF_4 , NSF_3, SF_1, H_2Sare reported. It is convincingly shown that in highly electronegative environment the energy levels of the sulfur 3d orbitals are reduced to the vicinity of those of the ligand valence orbitals and theirspatial distributions are contracted to the bonding area, and therefore can can participate in bondformation to a certain extent, which is enhanced by the formation of the dp π back bonds. Itseems that the result reported in this paper is helpful for the solution of the long-standing debateabout the sulfur 3d orbital participation in bond formation.