The oxidized platinum (Pt) can exhibit better electrocatalytic activity than metallic Pt 0 in the hydrogen evolution reaction (HER), which has aroused great interest in exploring the role of oxygen in Pt-based catalysts. Herein, we select two structurally well-defined polyoxometalates Na 5 [H 3 Pt (IV) W 6 O 24 ] (PtW 6 O 24 ) and Na 3 K 5 [Pt (II) 2 (W 5 O 18 ) 2 ] (Pt 2 (W 5 O 18 ) 2 ) as the platinum oxide model to investigate the HER performance. Electrocatalytic experiments show the mass activities of PtW 6 O 24 /C and Pt 2 (W 5 O 18 ) 2 /C are 20.175 A mg −1 and 10.976 A mg −1 at 77 mV, respectively, which are better than that of commercial 20% Pt/C (0.398 A mg −1 ). The in situ synchrotron radiation experiments and DFT calculations suggest that the elongated Pt-O bond acts as the active site during the HER process, which can accelerate the coupling of proton and electron and the rapid release of H 2 . This work complements the knowledge boundary of Pt-based electrocatalytic HER, and suggests another way to update the state-of-the-art electrocatalyst.