Exploring superior electrocatalyst for hydrogen evolution reaction (HER) is an urgent need for hydrogen production based on water splitting. The redistribution of electrons and the increase of active sites through multi-interface designing of electrocatalyst are powerful strategies to improve the catalytic efficiency. Herein, a three-phase interface structure of N,P co-doped carbon tube embedded with MoO₂/Mo₂C (MoO₂/Mo₂C-CT) was fabricated via a cooperative polymerizing-embedding and pyrolysis strategy. Work function and X-ray photoelectron spectroscopy (XPS) verified that the interfacial charge was quantificationally modulated, achieving an intrinsically enhanced charge transfer by an induced built-in electric field. Theoretical study of density functional theory (DFT) illustrated that triple-interface structure showed a lower energy for H* + H₂O* than that of single-interface counterparts. The triple-interface MoO₂/Mo₂C-CT delivered a lower overpotential of 129 mV at 10 mA·cm⁻² than that of either single-interface MoO₂-CT or Mo₂C-CT catalyst. This work may put forward an attractive approach for modulating electronic structure and provide insights into the understanding of triple-interface structure towards HER.