In pulp bleaching operations using magnesium hydroxide instead of caustic soda, and with the traditional bleaching process for review and comparison, laboratory tests show that the use of magnesium hydroxide can maintain the brightness of the pulp, improve the viscosity of the slurry, reduce COD content and production costs. In the pulp bleaching process with hydrogen peroxide, using magnesium oxide or magnesium hydroxide instead of caustic soda can reduce the content of iron and manganese ions in the pulp, the former can be reduced to 2mg/L, the latter 10mg/L, and improve the quality of the pulp (to avoid yellowing due to the presence of excessive iron). At the same time has a buffer effect, pH value is easy to control, if with the use of inorganic complexing agent phosphate, silicate effect is better.