The invention provides a preparation method of p-anisidine, and belongs to the technical field of
chemical synthesis. The method comprises the following steps: firstly, adding a predetermined amount of
methanol and a catalyst into a hydrogenation kettle, replacing, removing
oxygen and activating the catalyst, and dropwise adding a
raw material p-nitroanisole into the hydrogenation kettle at a predetermined
hydrogen pressure and a predetermined
reaction temperature to carry out a
hydrogenation reaction. According to the method, in the process of reducing the use amount of
methanol and dropwise adding p-nitroanisole for
hydrogenation reaction, the concentration of p-nitroanisole in a hydrogenation kettle is always kept at a lower level, the
solvent and the catalyst are sufficient, p-aminoanisole which is continuously generated is utilized to play a role of the
solvent, the substrate reaction is more thorough, the reaction time is greatly shortened, and the generation amount of byproducts is reduced. Experiments show that the single-kettle
hydrogenation reaction time is shortened by 30%-47%, the single-kettle productivity can be improved by 33%-97%, meanwhile, the single-kettle reaction time is shortened, the daily productivity can be improved by 77%-125%, and the purity of p-anisidine in the product reaches 99.3%-99.7%.