The invention discloses an N-doped graphene/nickel ferrite nanometer compound material and a preparation method thereof. The preparation method comprises the following steps: performing ultrasonic dispersion on graphite oxide in water, thereby acquiring a graphite oxide solution; adding ferric nitrate and nickel nitrate into the graphite oxide solution and continuing to perform ultrasonic dispersion; adding urea into the mixed solution; transferring the mixed solution into a three-neck flask; after oil-bath heating reaction, centrifugally washing and drying a product, thereby acquiring the N-doped graphene/nickel ferrite nanometer compound material. According to the method, the urea is adopted for reducing the graphite oxide; while reducing, nitrogen atoms are doped on the surface of the graphene; the surface chemical property of the graphene is changed and the surface defect of a chemical method for preparing the graphene is overcome by the doping of the nitrogen atoms; alkalinity is supplied through the urea hydrolysis, so that nickel ferrite is formed on the surface of the N-doped graphene; the accumulation and agglomeration of the graphene in layers can be further stopped by the nanometer particles of the nickel ferrite, so that the electrochemical property of the compound material is increased.