The invention discloses a relatively high-stability catalyst for propylene preparation by propane dehydrogenation. A composite oxide aluminum oxide-chromium oxide is taken as a composite carrier, metal Pt is taken as an active component, metal Sn, La and Y are taken as assistants, a chemical formula of the catalyst is Pt-Sn-La-Y/Cr2O3.Al2O3, the mass ratio of Cr2O3 to Al2O3 in the composite carrier is 2:1, and the catalyst contains 0.2 to 1.0wt% of the Pt, 0.4 to 1.5wt% of the Sn, 0 to 1.4wt% of the La and 0.2 to 1.2wt% of the . The catalyst has the advantages that a preparation method is simple in process and easy to implement, the prepared catalyst has relatively high propane conversion rate, relatively high activity and relatively long service life, and the catalyst stability is remarkably improved; the propylene selectivity is relatively high, the catalyst deactivation coefficient is small, remarkable economic and technical effects are achieved, and industrialized popularization is facilitated.