Abstract: The four Hydrogen-Bonded systems of C≡N—H…OH_2, N≡C—H…OH_2 and H—N≡C…H—OH,H—C≡N…H—OH have been studied with ab initio LCAO-MO-SCF methods at 4-31G level. The complete structure optimization have been carride out. We have also performed the Morokuma's Energy Decomposition Analysis for these four systems.The results show that, the electrostatic interaction (ES) is the most important attractive component in the H-Bond and the charge transfer interaction (CT) is the next largest attractive one. In most cases the order of ES can determine the H-Bond strength order betreen similar systems such as C≡N…H—OH_2 N≡C_2. But in some particular cases, we must consider both ES and CT to predict the order of H-Bond strength, such as H—N≡C…H—OH and H—C≡N…H—OH. We have discussed that the energy components are strongly distance dependent. At relatively small separations, the ES, CT, PL can all be important attractive components. At longer distance for the same systems the relative importance of the CT interaction maybe increased.