provided is a method for preparing methanol and diol from cyclic carbonate , comprising : under a hydrogen atmosphere , in an organic solvent , and with the presence of a ruthenium complex xyy ′) and an alkali , conducting a hydrogenation reduction reaction on the cyclic carbonate or polycarbonate to obtain methanol and diol . also provided is a ruthenium complex prepared from ruthenium and a tridentate amido diphosphine ligand . also provided is a deuterated methanol and deuterated diol preparation method by substituting the hydrogen and ruthenium complex with deuterium .