The invention relates to a method and a device for effectively removing acid in tail gas during the process of preparation of alcohol sec-butyl acetate by utilization of liquefied petroleum gas to be mixed with n-butene in c_4 olefin and react with an acetic acid. The method takes an alkali solution as a solvent to remove the acetic acid in released tail gas in an extracting tower during the process of production of the alcohol sec-butyl acetate by adoption of the n-butene in the liquefied petroleum gas as a raw material; the liquefied petroleum gas after removal of the acetic acid is sent into a gas-liquid settling tank again, and enters into a torch pipe network system after separation of an alkali solution; and a tail gas system of the whole device is isolated from an external device through a liquid seal which is arranged on the gas-liquid settling tank. The method and the device guarantee that the tail gas after deacidification can safely enter into a gas holder and a torch system which do not resist acetic acid corrosion, save the trouble of needing to match a newly-built torch system which resists acetic acid corrosion and the gross investment of the newly-built device.