The invention discloses a preparation method of a CoFe2O4 / AC microbial fuel cell air cathode catalytic material. The preparation method comprises the following steps: A, preparing an iron-cobalt liquid: weighing cobalt chloride and iron chloride, adding a mixed solution of deionized water and ethylene glycol, and stirring to obtain the iron-cobalt solution; B, weighing activated carbon, ultrasonically dispersing in the obtained solution and stirring; C, dropwise adding ammonia water to the obtained solution, sealing the opening of a beaker by a fresh-keeping film, rising temperature and stirring; D, transferring an obtained suspension to a reactor, putting in an electric oven after sealing, and reacting; E, collecting obtained products: taking the reactor out, filtering after cooling to room temperature, cleaning with ethanol and deionized water repeatedly, and placing in the electric oven to be dried overnight; F, placing obtained dried solid materials in a porcelain boat, putting in a tubular furnace, cooling to the room temperature to obtain a nanometer mixture, namely a CoFe2O4 / AC catalyst. The CoFe2O4 / AC microbial fuel cell air cathode catalytic material is simple in process, easy to control process parameters, low in cost, good in dispersion, more in active sites and obvious in catalytic performances.