The present invention relates to a chlorinated polypropylene modified waterborne acrylic resin with an excellent water boiling resistance performance, a preparation method thereof and a coating material. The chlorinated polypropylene modified waterborne acrylic resin is prepared from the following raw materials in mass percentages: 5-20% of a cosolvent, 2.5-15% of chlorinated polypropylene, 4.5-10% of a hydrophilic monomer, 5-20% of a functional monomer, 0.05-3% of an initiator a, 5-30% of a vinyl monomer, 0.05-3% of an initiator b, 3-12% of a neutralizer and 25-45.45% of deionized water. Thechlorinated polypropylene component and an acrylic resin component are combined by graft copolymerization to improve adhesion of the resin to a non-polar polyolefin substrate, and a two-step droppingmethod is used to gather the functional monomers with relatively strong hydrophobicity and relatively large steric hindrance together to ensure that the resin has excellent adhesion and at the same time has the excellent water boiling resistance performance.