Abstract: The effect of alkalineearth promoters on the catalytic properties of supported PtSn/γ-Al2O3 catalysts for longchain paraffin (C10~13) dehydrogenation has been studied by using infrared spectroscopy of adsorbed pyridine (Py-IR), thermalgravimetry (TG), H2 chemisorption and temperatureprogrammed reduction (TPR) combined with microreactor tests. The results show that addition of alkalineearth metal (Mg, Ca, Sr, Ba) to PtSn/γ-Al2O3 can improve its catalytic stability for paraffin dehydrogenation by decreasing the amount of coke formed on the catalysts and increasing the fraction of bare metallic Pt surface after carbon deposition．However, coaddition of alkalineearth metal with higher basicity, e.g. Ba2+, results in stronger interaction between Sn and support, leading to weaker interaction between Pt and Sn and decrease of bare fraction of Pt after carbon deposition. As a result, the PtSnBa/γ-Al2O3 catalyst shows a lower catalytic activity for longchain paraffin dehydrogenation.