The invention relates to a quick mounting device of a terminal strip. According to a first embodiment of the invention, the device comprises a casing, a metal connecting piece arranged in the casing and a cable pressing device and a connecting device which are arranged on the casing; and on the basis of not disconnecting an original direct current power supply, the terminal strip is reliably connected on the top of an original terminal strip to fundamentally guarantee the safe and stable operation of a direct current system. According to a second embodiment of the invention, the device comprises a metal connecting piece, an L-shaped baffle fixedly arranged at the bottom of one side of the metal connecting piece, a fastening bolt screwed on the middle part of the metal connecting piece andan adjusting bolt screwed on the other side of the metal connecting piece; and the terminal strip is firmly mounted on an original terminal strip guide rail through the metal connecting piece and a U-shaped rail or a G-shaped rail and the step of removing the original guide rail is saved. The device disclosed by the invention has the positive effects that the structure is simple; the installationand the adjustment are convenient; and the work efficiency is greatly improved.