Abstract: Pt-Sn_E/Mg (Al) O catalyst was prepared by anion exchange method with hydrotalcite as the support. The Pt-Sn_E/Mg (Al) O catalyst was characterized by XRD, nitrogen sorption, CO-TPD and TEM; its catalytic performance in the dehydrogenation of ethane and propane was compared with that the Pt-Sn_I/Mg (Al) O catalyst obtained by impregnation method. The results indicate that under the same reaction conditions, the conversions of ethane over the Pt-Sn_E/Mg (Al) O and Pt-Sn_I/Mg (Al) O catalysts are 12.2% and 3.1%, respectively, whist the conversions of propane over these two catalysts are 38.7% and 26.4%, respectively. Such results illustrate that the Pt-Sn_E/Mg (Al) O catalyst prepared by the anion exchange method is obviously superior to the Pt-Sn_I/Mg (Al) O catalyst prepared by the impregnation method in terms of catalytic activity and stability for alkane dehydrogenation.