Controlling　the　morphology　of　Pt-Au　bimetal　nanostructures　can　provide　a　great　opportunity　to　increase　their　catalytic　activity　on　a　Pt　mass　basis　and　improve　their　durability　at　the　same　time.　In　this　study,　we　synthesized　Pt-on-Au　hollow　urchinlike　nanoparticles　(NPs),　which　present　a　structure　consisting　of　a　monolayer　of　small　Pt　NPs　uniformly　overgrown　on　an　Au　hollow　nanourchin　(HNU).　The　Pt-Au　HNUs　demonstrated　an　ultrahigh　density　of　sharp　tips　and　uniform　coating　of　2　nm　Pt　NPs.　This　well-controlled　bimetal　nanostructure　exhibited　a　large　electrochemical　surface　area,　more　than　2　times　higher　than　that　of　Pt　black,　and　a　relatively　high　electrocatalytic　activity　toward　the　methanol　oxidation　reaction,　more　than　3　times　greater　than　the　Pt　black　and　Pt/C　commercial　reference　catalysts.　Simultaneously,　the　Pt-Au　HNUs　showed　greatly　improved　durability　because　of　the　small　Pt　NPs　on　the　surface　of　Pt-Au　HNUs　which　were　effectively　stabilized　by　the　Au　metal　support.