Studying the adsorption properties of the porous magnesium oxide, which providing theoretical basis for its application in sugar industry. The porous magnesium oxide was synthesized by burnning the porous hydromagnesite which was synthesized by stir-the ageing method. By studying remel syrup of brown granulated sugar as the object, exploring the feasibility of the process of decolorization by the porous magnesium oxide. Through decolorization rate as the index, evaluation of variables effects such as the porous magnesium oxide dosage, preliming pH value, adsorption time, adsorption temperature for the decolorization for the remelt syrup of brown granulated sugar. the results showed that the optimal process conditions for the decolorization rate were:the porous magnesium oxide dosage:0.1 g, adsorption temperature60 ℃, adsorption time:60 min, preliming pH value:8.00, Under these optimal conditions, the decolorization rate:84.7% .The porous magnesium oxide was used to further investigations. The adsorption kinetics of the porous magnesium oxide was consistent with Lagergren equation Ⅱ. Moreover, the adsorption isotherm also complied with the Langmuir equation.