The invention relates to a method for producing sec-butyl acetate by synthesizing acetic acid and mixed C4, which belongs to the chemical field. The invention aims to provide the method for producing the sec-butyl acetate by synthesizing the acetic acid and the mixed C4, which is used for fully and reasonably utilizing byproduct mixed C4 resources of petrochemical enterprises, broadening the way to comprehensively utilize C4 hydrocarbon, and producing fine chemical products with high added value. According to the invention, a kettle type batch reactor is adopted, strong-acid cation exchange resin is adopted as solid catalyst, the acetic acid and the mixed C4 are used as the raw materials to synthesize the sec-butyl acetate, the reaction pressure is 2.0-6.0MPa, the reaction temperature is 80-160 DEG C, the reaction time is 5-15h, the molar ratio of olefine acid is 0.2-1.5, and the catalyst amount is 4-12 percent of the acetic acid. According to the synthetic process of the sec-butyl acetate, the acetic acid and butane (refinery byproduct mixed C4 contains 1-butane and 2-butane) are adopted as the raw materials to be directly synthesized through addition reaction under the action of acid catalysts, an olefin resource is directly utilized, and ethanol is unnecessary to be an intermediate, so that the production cost of the sec-butyl acetate is reduced, the obvious economic advantage is achieved, the refinery mixed C4 resource is effectively utilized, and the method is an effective way to improve chemical utilization of C4 hydrocarbon.