2,5-Furandicarboxylic acid (FDCA), as an important monomer to produce biodegradable polymers, is a hot compound in the field of electrocatalysis. Designing high-activity and low-cost electrocatalysts for the production of high concentration FDCA is an urgent and challenging task. Here, a cactus-like NiCoP nanoplate was prepared as a robust electrocatalyst to enable 5-hydroxymethylfurfural (HMF) oxidation to FDCA at high concentration. In situ Raman spectroelectrochemical analysis investigated the dynamic structural evolution of the NiCoP surface during the electrooxidation of HMF. The substituted Co atoms make the NiOOH active species easier to form on the NiCoP surface than Ni₂P at low constant voltage, which promotes the oxidation of HMF into FDCA. The total potential of coupling the cathodic H₂ reduction reaction with the anodic HMF oxidation reaction (HMFOR) is only 1.464 V when NiCoP is the electrode material. The design of the flow-through mode reactor optimized the mass transfer process in the reaction, and further improved the coupling efficiency. The conversion rate of HMF and yield of FDCA reach 98.7% and 98.8%, respectively, even when the concentration of HMF is as high as 300 mM.