The invention discloses a catalyst for preparing 2,3,3,3-tetrafluoropropene from 2-chloro-1,1,1,2-tetrafluoropropane. The catalyst is expressed as A-B-C/M, wherein M is a carrier, A is an active component, and B and C are cocatalysts; the carrier is composed of one or more of magnesium oxide, magnesium fluoride, magnesium carbonate and basic magnesium carbonate; the active component is one of cesium fluoride, cesium chloride, cesium nitrate and cesium hydroxide, and the content of the active component is 1-15% of the mass of the carrier; the cocatalyst B is one of strontium chloride, strontiumnitrate, barium chloride and barium nitrate, and the content of the cocatalyst B is 0.5-10% of the mass of the carrier; the cocatalyst C is one of yttrium nitrate, lanthanum nitrate and cerium nitrate, and the content of the cocatalyst C is 0.1-5% of the mass of the carrier; and active component A and the cocatalysts B and C are loaded on the carrier M by adopting a co-impregnation technology ora step-by-step impregnation technology, and then the obtained material is dried and calcined to obtain the required catalyst. The catalyst has the advantages of high activity, high in HFO-1234yf selectivity, low preparation cost and industrial application values.