The invention discloses a preparation method of porous nano CoFe2O4. The method comprises the following steps: under the condition that the mass percentage of a ferric salt, a cobalt salt, alkali, deionized water, an organic solvent and a sublimable compound template is (0.001-70%):(0.00001-70%): (0.001-55%): (0.001-90%):(0.001-90%):(0.001-90%), reacting a mixed solution of the ferric salt and the cobalt salt with an alkali solution, and carrying out separation and purification on the obtained object so as to obtain a CoFe2O4 sol; and mixing the CoFe2O4 sol with the deionized water, carrying out ultrasonic dispersion on the obtained mixture, adding the organic solvent and the sublimable compound template, reacting by using a water-organic solvent mixed solvothermal method, distilling the obtained object so as to remove a mixed solvent, carrying out heat treatment on the obtained product so as to remove the sublimable compound template, and then sequentially cooling, grinding, washing, filtering, drying and grinding the obtained product, so that porous nano CoFe2O4 powder is obtained. The method is simple and feasible in process, small in investment, and beneficial for popularization and utilization.