The invention discloses a molybdenum-containing stainless steel and a smelting method thereof. The molybdenum-containing stainless steel comprises, by mass, 0.023% or less of C, 0.42-0.50% of Si, 1.35-1.45% of Mn, 0.030% or less of P, 0.002% or less of S, 16.55-16.70% of Cr, 10.05-10.15% of Ni, 0.025% or less of N, 2.09-2.15% of Mn, and the balance Fe and residual elements. The smelting method of the molybdenum-containing stainless steel comprises the steps of AOD refining, tapping to ladles, LF refining and continuous casting, wherein the AOD refining step is characterized in that molten iron is added, then molybdena spheres and lime are added to an AOD converter, eight processes of a decarburization reaction are carried out, and finally reduction and desulphurization are carried out. MoO3 reacts with CaO in the AOD converter to form CaMoO4 which has a high melting point and is nonvolatile, the high temperature of the molten iron in the converter can rapidly melt the molybdena spheres, and the elements comprising C, Si, Mn, Fe and the like in the molten iron and a good dynamics stirring condition in the AOD converter are utilized to reduce the molybdena spheres to realize rapid reduction of molybdena and the direct alloyage of the molybdena in the molten iron, so the method has the advantages of low production cost, simple operation and easy control.