Herein, we present Pt-M/C(M=Fe, Co, Ni) nanoparticle with PtO₂ and Pt(acac)₂ precursor for oxygen reduction reaction(ORR) in acidic media and compare their mechanistic difference in synthesis process and catalytic performance caused by it. It was synthesized with sonochemical method that is simple one-step reaction and it is useful to control the metal composition. In structural study, their particle size is 2-3 nm and well-dispersed on carbon support and EDS line mapping data underpin that they synthesize core-shell nanoparticle. In case of PtO₂ precursor, Pt-Ni also synthesized well compare with Pt(acac)₂ precursor and they make oval shape nanoparticle in all case of transition metal unlike Pt(acac)₂ case that make sphere shape particle. Compared their activity, sample synthesized with Pt(acac)₂ show better activity than PtO₂ and both of that better than that of commercial Pt/C. In durability test, sample with PtO₂ better than that of Pt(acac)₂. In sonochemical method, difference of Pt precursor guides different mechanism to synthesize nanoparticle from precursor. We propose that Pt(acac)₂ exist ion form in solution when before Pt reduce from precursor to metal and it can be occurring gavalnic replacement with Fe. While PtO₂ can’t be dissolved because it is ionic compound, therefore it makes aggregated Pt particle that is the reason why it is hard to replacement with Fe.