The realistic structures of pure, Cr and Se substituted MoS2 nanostructures are optimized and simulated successfully with B3LYP/ LanL2DZ basis set. The stability of MoS2 nanostructures are discussed in terms of calculated energy. The point symmetry and dipole moment of both pure and impurity substituted MoS2 nanostructures are also reported. The electronic properties of MoS2 nanostructures are discussed by HOMO – LUMO gap, electron affinity and ionization potential. The results of the present work will give insights to tailor MoS2 nanostructures by substitution impurities and defect structure which enhances the electronic properties and structural stability of MoS2 nanostructures that find its key application in photo catalysis, photovoltaic cells and dry lubrication.