The present invention relates to a vinyl chloride-vinyl acetate copolymer exhibiting excellent tensile strength even at low processing temperatures, and a preparation method therefor. According to the present invention, the copolymer comprises a vinyl acetate-derived unit in a specific ratio, and has a polydispersity index of a specific range, for example, a polydispersity index of 2.1-2.4, in the range of a degree of polymerization of 1,200-1,300, so as to exhibit excellent tensile strength even in low-temperature processing. Therefore, according to the present invention, the vinyl chloride-vinyl acetate copolymer and a preparation method therefor can be readily applied to an industry requiring the same, particularly, the automotive industry or the polyvinyl chloride resin industry.