Ribbons of nanocomposite Pr2(FeCo)14B/α-(FeCo) with an additive of low melting point metals, such as Al, Zn, Sn or In, were prepared by melt spinning. It was found that the remanence could be obviously improved at the expense of coercivity by the addition of Sn. The remanence Jr about 1.30 T and maximum energy product (BH)max about 20.5 MG Oe were obtained in Pr9Fe74Co12B5 doped with 0.5% Sn, while Jr and (BH) in the ribbons without the additive were about 1.17 T and 17.9 MG Oe, respectively. The additive Sn is located at the grain boundaries rather than in grain interior in the ribbons. The obvious improvement of the remanence originates from the refinement of the microstructure and the increase of soft phase content by the addition of Sn. The effect of additive Sn on the coercivity was also discussed. By increasing the content of the magnetically hard phase, the intrinsic coercivity iHc can be elevated. Thus, the optimum magnetic properties, such as Jr = 1.27 T, iHc = 5.7 kOe and (BH)max = 22.5 MG Oe, were obtained in Pr9.5Fe73.57Co11.93B5 ribbons doped with 0.5% Sn.