Herein, we report a kind of NiCu-based composite phosphides electrocatalyst(NiCuP/NM), which was prepared in situ on nickel mesh substrate by one-step hydrothermal method with NaH₂PO₂, CuSO₄, NiSO₄ as initial materials. The morphology, crystal structure, composition, and electrocatalytic performance of NiCuP/NM were characterized. Under the optimal preparation conditions of Ni, Cu and P(molar ratio 8 : 1 : 20), hydrothermal synthesis at 140 ℃ for 24 h, the obtained composite electrocatalyst displayed three-level micro-nanostructure with Ni₂P and Cu₃P as main crystal phases. At the current density of 10 mA·cm ^-2, the required HER (Hydrogen Evolution Reaction) overpotential and HzOR (Hydrazine Oxidation Reaction) potential of NiCuP/NM were 165 and 49 mV, respectively. In the two-electrode system, the decomposition tank pressure for the NiCuP/NM cell at the same current density was only 0.750 V which remained substantially unchanged for 24 h catalysis, exhibiting excellent catalytic stability. NiCuP/NM displays prominent electrocatalytic performances towards HER or HzOR in both three-electrode and two-electrode systems, which can be ascribed to two aspects. On the one hand, the 14-fold electrochemical active surface area compared with original nickel mesh enables NiCuP/NM expose huge number of catalytic active sites in both HER and HzOR. On the other hand, the electronic structure modification of Ni and Cu atoms induced by doping P atom brings great improvement of intrinsic HzOR activity of electrode materials. This study provides a new perspective for nanoscale synthesis and promotes the development of novel nanopores in fuel cell and energy conversion applications.