The invention relates to a jacking unit for beam falling of a railway precast beam. The jacking unit comprises a bottom plate, a vertical adjusting device which is arranged on the bottom plate and used for adjusting the vertical position and a horizontal adjusting device connected with the vertical adjusting device. The jacking device is provided with the horizontal adjusting device and the vertical adjusting device, so three-way displacement adjustment is achieved; the jacking unit is simple, reliable, high in precision, high in efficiency, safe and reliable. In use, the jacking unit is placed on a bridge pier, a precast beam is lifted to the upper part of the jacking unit to support the bridge, and the position of the bridge in three directions can be adjusted through three-way displacement adjustment, so accurate positioning of the bridge is achieved, and the adjusting efficiency is high.