The invention relates to a device and method for preparing 2,3,3,3-tetrafluoropropylene. The device for preparing the 2,3,3,3-tetrafluoropropylene comprises a first reactor, a first rectifying tower group, a second reactor, a second rectifying tower group, a crude product pot and a third rectifying tower group which are successively installed forward and backward. According to the device and method for preparing the 2,3,3,3-tetrafluoropropylene, two types of different catalysts are loaded in the second reactor, and two reactions are performed simultaneously, so the technological process is simplified; the reactions are a gas-phase reaction, so the problems that the age of a liquid phase reaction catalyst is short and the corrosion of the reactor is serious are effectively solved; and the reaction process is simple, so the equipment investment and the energy consumption are reduced.