Sucrose was pyrolyzed on gamma alumina surface to prepare carbon covered alumina (CCA) material. Alumina and CCA supported Pt–Sn catalysts were prepared by the complex impregnation method under vacuum. Dehydrogenation of n-octadecane was performed to study the effect of carbon addition, Pt loading and Sn/Pt weight ratio on the catalytic dehydrogenation activity, selectivity and catalyst stability. BET, mercury porosimetry, XRD, CO-chemisorption, TPR and TG-DTA were used for the carrier and the corresponding catalyst characterization. The results showed that more carbon addition, Pt loading and higher Sn/Pt ratio are propitious to the mono-olefin selectivity and catalyst stability. Pt–Sn was easily formed on the Pt–Sn/CCA catalysts, especially when the Pt loading and Sn/Pt ratio were very high. To keep optimal dehydrogenation conversion, taking consideration to good selectivity and stability, the carbon content, Pt and Sn loading of Pt–Sn/CCA catalysts should be 8.37 wt.%, 0.5 wt.% and 3 wt.%, respectively.