Electronic structure design to optimize the hydrogen adsorption/desorption balance on the catalysts plays a key role in improving the catalytic efficiency of the low-load Pt-based catalyst in the hydrogen evolution reaction (HER). In this study, we modulate the electronic structure of Pt nanoclusters through tuning the interface of Pt/SnO2 clusters confined into nitrogen-doped porous carbon for enhanced hydrogen evolution catalysis. Theoretical calculations reveal that adjusting the contact distance between Pt and SnO2 generate stronger electron coupling and more free electrons transfer to Pt, and thus downshift Pt d-band center, which balances the intermediate H* adsorption/desorption on the Pt site, thus accelerating HER catalytic process. As a result, in acidic solution, the optimized catalyst (Pt/SnO2@NPC-300) showed significantly enhanced HER catalytic activity with the minimum overpotential (11.7 mV) at 10 mA·cm−2, the highest mass activity (4.08 A mgPt-1)at 10 mV and the turnover frequency (4.13 s−1) at 20 mV, far superior to that of Pt/NPC and commercial Pt/C catalyst. Our work provides a reference for the precise design of low-Pt nanocluster catalysts with high HER activity and durability.