The invention discloses a preparation method of organoacetoxysilane, which adopts organochlorosilane and acetic acid as raw materials. The method comprises the following steps: the organochlorosilane and an organic solvent are added into a reaction vessel and the organic solvent is selected from one of solvent naphtha, hexane, hexamethylene, toluene, xylene and dichlorethane. The acetic acid is slowly added into the reaction vessel and reacted with the organochlorosilane and boiled for eight hours to obtain organoacetoxysilane solution; the organic solvent in the organoacetoxysilane solution is distilled at ordinary pressure and then recycled. Matters with low boiling point, remaining in the reaction vessel, are removed by distillation at reduced pressure to obtain colorless and transparent finished products. As the acetic acid has lower cost than acetic oxide and the preparation method of the invention optimizes each technological parameter, the preparation method of the invention ischaracterized by low cost, high efficiency, and good quality, etc. In the obtained finished product, the effective content of organoacetoxysilane is more than 93 percent while the content of chloridion is less than 50PPM.