The invention aims to provide a preparation method of a
chromium-doped
cobalt phosphide nanorod array growing on carbon cloth in situ, which comprises the following specific steps of oxidizing the carbon cloth in
nitric acid to enhance the hydrophilicity of the carbon cloth, and growing a layer of precursor CrxCo1-x(OH)F / CC on the carbon cloth in situ by a hydrothermal method, finally, converting the precursor growing on the carbon cloth into
chromium-doped
cobalt phosphide CrxCo1-x(OH)F / CC through a high-temperature gas-phase phosphating method. The preparation process is simple to operate, easy to control and low in cost and can be used for large-scale production, the
chromium-doped
cobalt phosphide nanorod array which grows on the carbon cloth in situ and is prepared by adopting the method is uniform in distribution and close in arrangement, the rod-like particle size reaches the nanoscale and is uniform in particle size, and the CoP
crystal form is reserved while the free energy of
hydrogen adsorption is reduced by
chromium doping; the
hydrogen evolution reaction can be efficiently, continuously and stably catalyzed.