The sluggish charge transfer and poor intrinsic activity are the obstacles that limit the development for electrocatalysts on hydrogen evolution. A novel core-shell heterostructure composed of Cu3P nanowires with supported CoO nanosheets was synthesized. Owing to numerous active sites and synergistic effect, the as-prepared Cu3P@CoO was highly efficient for hydrogen evolution and outperformed the single component. The theoretical calculations demonstrate that Cu3P@CoO had a zero bandgap for the incorporation of metallic Cu3P, which can greatly accelerate the charge transfer. Besides, the adsorption free energy of intermediates on Cu3P@CoO can also be optimized, leading to a small energy barrier in the reaction pathway, and thereby an increased intrinsic activity. This work highlights the significance of exploiting the synergistic effect of the heterostructure on the charge transfer and intrinsic activity when designing highly efficient electrocatalysts for hydrogen evolution.