Several PVP-stabilized colloidal platinum metals nanoparticles have been synthesized and characterized by FTIR and TEM. Comparing with the pure PVP, carbonyl groups of PVP in the mixture of PVP and the metal precursors or in the PVP-stabilized metal nanoparticles have obvious peak shifts in FTIR spectra. The peak shifts reveal the interaction between PVP and the metal species. The interaction between PVP and metal precursors has effect on the formation of the colloidal metal nanoparticles. Strength of the interaction between PVP and metal nanoparticles has direct influence on the stability and the size of the PVP-stabilized metal nanoparticles. Therein, species of the metal precursors and amount of the stabilizer are main factors on the strength of the interaction.