Abstract: An oxygen bleaching method of pulp includes the steps of: adding a solution formulated by a magnesium salt and an activator to an unbleached chemical pulp, stirring to be mixed well, and bleaching by introducing oxygen. The activators are nano zero-valent metals that are conventional, low-cost, and recyclable. These activators can activate low-concentration oxygen at low-temperature in neutral aqueous solution to efficiently generate peroxide anion radicals, so as to promote the generation of hydroperoxide anions and peroxide ions, achieving high efficient delignification. The whole process does not generate waste water, the oxygen consumption is only 50-85% of the original process, the yield is increased by 1.5-2.8% compared with the original system, the pulp brightness is increased to 28-32° SR, and the magnesium salt can be recycled and reused.