Magnesium-based alkalis for hydrogen peroxide bleaching of chemithermomechanical pulp from masson pine are investigated. The results show that the optimum conditions for magnesium-based alkalis for hydrogen peroxide bleaching of masson pine CTMP are as follows, hydrogen peroxide concentration 4 %, Mg （OH）2 concentration 1. 2 %, Na2SiO3 concentration 1.5%, time 120 min, temperature 80 ℃. Under the optimum conditions, the brightness of bleached pulp would reach 63. 5% （ISO）, while the brightness of pulp bleached by using the NaOH as alkali is only 61.4M （ISO）. Compared with NaOH-based bleaching, the CODe, of effluent from bleaching process is cut down by 38. 12% in Mg （OH）2-based hydrogen peroxide bleaching.