Abstract: Provided is a method of preparing a vinylchloride-based copolymer for plastisol processing. Suspension copolymerization of a vinylchloride monomer with a comonomer having a low glass transition temperature in the presence of a buffer added at an initial stage of the copolymerization can produce a vinylchloride-based copolymer resin with a good low-temperature melting property, a uniform particle size, and a narrow particle size distribution. A plastisol including the vinylchloride-based copolymer resin as a blend resin has low viscosity, and thus, can be easily processed even at a low temperature.