The invention discloses a preparation method of environment-friendly fuel oil, and belongs to the technical field of environment-friendly energy. The preparation method of the environment-friendly fuel oil comprises the procedures of preparing all components of environment-friendly raw materials, removing impurities in mineral oil, preparing lignocellulose powder, dispersing three times and the like to obtain the finished product of the environment-friendly fuel oil. According to the preparation method of the environment-friendly fuel oil, the environment-friendly fuel oil comprises mineral oil, vegetable oil, oleic acid, ethanolamine, isobutanol, ferrocene, a surfactant, lignocellulose and an auxiliary agent, and is prepared by adopting the combination of the mineral oil and the vegetable oil as a main material and adopting a plurality of auxiliary materials and auxiliary agents as auxiliary materials through the procedures of impurity removal, dispersion and the like, the preparation method is simple, and the prepared fuel oil has the advantages of low pollution, high combustion efficiency, good energy-saving effect and the like.