The invention relates to a preparation method of a flame resistance core-shell type aqueous acrylic ester resin coating. Water, emulsifiers, methacrylic acid and a monomer A are added and emulsified, an initiator starts to be added dropwise for 1-3 hours when the temperature is 75 DEG C, reaction is carried out for 3-5 hours with the temperature kept at 75 DEG C, quaternary phosphonium salt is added to react for 1-3 hours, and core layer emulsion is obtained; a monomer B and an initiator are added into the core layer emulsion dropwise for 1-3 hours at the same time and react for 2 hours with the temperature kept at 75-85 DEG C, borane is added dropwise, reaction is carried out for 1-3 hours with the temperature kept at 75-85 DEG C, then cross-linking agents are added dropwise, reaction is carried out for 1-2 hours with the temperature kept at 75-85 DEG C, the temperature is decreased to be 50 DEG C, an emulsifier is added into a reaction system, the reaction time is 30 minutes, ammonium hydroxide is added to adjust the pH value to be 7-8, and the flame resistance core-shell type aqueous acrylic ester resin coating is obtained. The flame resistance of obtained flame resistance core-shell type aqueous acrylic ester resin can be greatly improved, and the defect that traditional acrylic ester resin is sticky at high temperature and crisp at low temperature is also overcome.