Disclosed is a catalyst for preparing 2,3,3,3-tetrafluoropropene by gas-phase hydrodechlorination, which solves the problem of the high costs and easy deactivation of traditional chlorofluorocarbon hydrodechlorination catalysts. The disclosed catalyst is characterized in consisting of an active component and a carrier, wherein the active component is a combination of one or more of the metals: Ni, Mo, W, Co, Cr, Cu, Ce, La, Mn and Fe. The catalyst in the present invention has excellent performance, high activity, good stability and a low reaction temperature, effectively reduces reaction energy consumption, and has industrial application value.