The invention discloses a method used for heterogeneous phase catalytic degradation of printing and dyeing waste water with ozone. According to the method, a manganese nitrogen doped cerium-based magnetic chitosan catalyst is adopted as a catalyst, wherein the special nanometer sheet structure of the active components of the catalyst and the doping of metal manganese element and nonmetal nitrogenelement are capable of providing the catalyst with high ozone catalytic degradation activity. Operation of the method is simple; cost is low; and degradation efficiency is high.