The invention provides a preparation method of a biodiesel solid catalyst, and the method comprises the following steps: 1) activation of alumina powder; and (2) preparation of the catalyst. The Ni / Zr-supported biodiesel solid catalyst is prepared by characteristic analysis by use of non steady coprecipitation technique, plant oil and methanol as raw materials are used to evaluate the effects of the biodiesel solid catalyst according to the method, and effects of the molar ratio of the raw materials, reaction temperature and reaction time on the conversion rate are inspected. Compared with traditional homogeneous catalysts, in the process of using, the catalyst has simple process and less pollution emissions and other advantages; and the catalyst prepared by the method has large specific surface area and high catalytic activity.