The invention relates to preparation and application of a nitrogen-doped carbon nanotube nickel-iron coated oxygen evolution catalytic material for water electrolysis. A general formula of the composite electrode material is Ni0.9Fe0.1@CNx, wherein CN is nitrogen-doped carbon, and x is greater than or equal to 0.01 and less than or equal to 0.1. The specific preparation method of the catalytic material comprises the steps of uniformly mixing nickel acetate and ferric chloride with citric acid and thiourea according to certain molar percentages, and then carrying out calcinations for 1-10h under an N2 gas flow rate of 10-100 mL/min at 600-900 DEG C to prepare the catalytic material. The preparation method provided by the invention effectively achieves one-step preparation of the Ni0.9Fe0.1@CNx oxygen evolution catalytic material with set ratios of Ni, Fe, C and N by an in-situ solid-phase method, and the product is nanotube-shaped, porous and large in specific surface area, and has excellent performance when being used as an oxygen evolution electrode material for water electrolysis. The method provided by the invention is convenient to operate, the process is simple and easy to control, raw materials are low in price and easy to obtain, and the catalytic material is suitable for large-scale production.