Strong interfacial coupling in the hybrid catalysts could enhance catalytic performances. In this work, N, P were co-doped in zeolitic imidazolate framework-67 (ZIF-67) derived Co-based materials (denoted as CoP/NC) via in-situ carbonization and phosphating strategy, which accordingly induced strong interfacial coupling, leading to promote the catalytic activity in overall water splitting. In detail, the CoP/NC-2 presents the overpotential of 98 and 139 mV for hydrogen evolution reaction (HER) in 0.5 M HSO and 1.0 M KOH at 10 mA cm, respectively, and 295 mV for oxygen evolution reaction (OER) in 1.0 M KOH at 20 mA cm, which is excellent during the non-noble metal-based catalysts. It also achieved a potential of 1.69 V (η) in the overall water splitting. Density functional theory (DFT) based calculation reveals that the in-situ N, P co-doping induced strong interface coupling, which enhances the interaction in the interface of catalysts and improves electron conduction. More importantly, it contributes to adjusting electronic structure and d-band center, optimizing the adsorption energy for HER and/or OER and improving the kinetics of water splitting reaction. This work sheds new light on the heteroatom doping strategy to construct bifunctional transition metal-based electrocatalyst with boosting electrocatalytic performance in energy conversion application.