The invention provides a method for preparing 2,4-dimethylaniline by continuous hydrogenation. The method comprises the following steps: a 2,4-dimethylnitrobenzene solution undergoes heat exchange, and then enters a reactor from the side surface, wherein a plurality of hollow hydrogen distribution tubes are arranged in the reactor, an interlayer between the hydrogen distribution tubes and the reactor is filled with a catalyst, and a large amount of small holes are arranged in positions, in contact with the catalyst, of the hydrogen distribution tubes; and hydrogen enters the distribution tubesfrom the upper ends, overflow through the holes, and is mixed with a raw material liquid, and a reaction is carried out in a catalyst bed to generate the product of 2,4-dimethylaniline, wherein the solvent of the 2,4-dimethylnitrobenzene solution is one or more of water, methanol and ethanol. Compared with conventional batch reaction technologies, the method adopting the unique reactor and process design can realize continuous and efficient conversion of the 2,4-dimethylnitrobenzene. The method allows the raw material conversion rate to be more than 90% and the selectivity of the product to be more than 98% after continuously running for 1000 h.