The invention discloses a method of separating sec-butyl acetate and C8 hydrocarbon compound through triphase azeotropic distillation. The method is characterized by including: adding methanol and water as azeotropic agents into sec-butyl acetate and C8 hydrocarbon compound, performing triphase azeotropic distillation separation in a distillation tower to obtain sec-butyl acetate at the bottom of the tower and to obtain a tri-element azeotrope of methanol, water and C8 hydrocarbon compound at the top of the tower; adding water into the tri-element azeotrope obtained for extraction, wherein water phase is a methanol water solution and organic phase is C8 hydrocarbon compound. Qualified sec-butyl acetate and C8 hydrocarbon compound are separated from byproduct mixed ester by utilizing triphase azeotropic distillation and liquid-liquid extraction, sec-butyl acetate higher than 99% can be obtained, and waste is changed into valuable materials, so that substantial reduction of production cost is facilitated.