Because wet biomass such as residues from food industry or sewage sludge usually contains plenty of protein，the experiments of glycine gasification in supercritical water were conducted，in which glycine was used as the model compound of protein. The catalytic mechanism of sodium carbonate，product characteristics of glycine gasification were investigated with coupled relation between reaction temperature and reaction time. The results showed that sodium carbonate could increase gasification efficiency of glycine，the yield and volume fraction of hydrogen，and the removal efficiency of chemical oxygen demand（COD）of liquid products. The catalytic effect of addition amount of 0.1% mass concentration was better than that of 0.2%.And the effect of sodium carbonate on hydrogen yield was greater than that on volume fraction. The catalytic mechanism of sodium carbonate for glycine gasification was different from that of alkali compounds which has been reported before. Sodium carbonate increased the hydrogen yield probably by accelerating the decarboxylation reaction of formic acid，which was a glycine hydrolysate. Glycine could almost be gasified completely. The gas products include H2，CO2，N2，CH4，C2—C3，in which hydrogen volume fraction could be higher than 50%，hydrogen yield could be up to 1.8 L·g-1，and more than half of hydrogen came from water. The liquid after reaction could be reused not only because it was clear and transparent but also because both the COD and pH values were met the quality standard of domestic water for miscellaneous use.