The invention discloses a high-performance copolymerized paste resin and a preparation method thereof. According to the technical key points, the method comprises the following steps of: feeding a certain quantity of chloroethylene monomers, vinyl acetate monomers, water, emulsifiers, oil-soluble compound initiators and molecular adjusting agents into a dispersing tank respectively; and performing micro-suspension copolymerization to obtain the copolymerized paste resin of which the average latex particle diameter is 0.3-2 mum, the content of vinyl acetate is 3-19 percent and the average polymerization degree is 1,400-2,300. Compared with a PVC (Poly Vinyl Chloride) paste resin prepared with a homopolymerizing method, the high-performance copolymerized paste resin has the advantages of low processing temperature, high processing speed, high processing fluidity, high plasticizer dissolving speed, strong bonding force with a substrate, high elasticity of a plasticized product, high strength and the like.