Effect of Pt impregnation on the textural properties, surface element distributions and catalytic behavior of a precipitated iron-based catalyst for Fischer-Tropsch synthesis (FTS) was investigated by N-2 physical adsorption, temperature-programmed reduction (TPR), Mossbauer effect spectrometer (MES), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Low levels of Pt addition lead to an increase in BET surface area. The result of XPS indicates that Pt enriches on the catalyst surface after being calcined. HRTEM shows that Pt crystallites with diameter about 2 nm are well dispersed on the surface of the catalyst (100Fe/1Pt/4 K/16SiO(2)). The results of TPR and MES clearly indicate that Pt facilitates the reduction and carburization of Fe2O3 to some extend. The reaction tests in a slurry reactor give the result that the Pt impregnation remarkably increases the FTS activity, and suppresses the selectivities of the light hydrocarbons and the olefins.