Using different precursors, two series of nano Pt/MgO catalysts (Pt-II and Pt-IV, respectively) loaded with Pt in a wide range from 0.1 wt% to 2.2 wt% were prepared by using wet impregnation methods. The physico-chemical properties of catalysts were characterized by using BET, XRD, TPD-CO2, and other techniques. The results revealed that the precursor and content of Pt, especially the acid/base properties of the precursor solution, had a big influence on the structure, and surface properties of the catalysts. The loaded Pt is in metallic state in all the catalysts calcined at 1073 K. The Pt-II catalysts had larger surface areas and relatively narrow pore size distribution range. The MgO crystals in the calcined Pt-II-3 catalyst had more regular structure than that in the calcined Pt-IV-3 catalyst.