The invention relates to a quick fixing device for a knife-switch overhaul platform, and belongs to the field of electricity high voltage isolator serving tools. The quickly fixed device comprises a frame. Fixed plates are separately installed on the frame, which are used for connecting ladder legs of the maintenance platform. The frame is provided with two pairs of hook legs which are relatively sliding. When the device is in use, the four channel-shaped fixed plates of the frame are connected with the ladder legs of the maintenance platform through bolts. The four hook legs installed on the frame can be adjusted left and right to adapt to the disconnecting links of different models. The quickly fixed device has the advantages of being simple and convenient to operate, flexible in movement, firm in fixation, high in safety, wide in application, and time-saving . The problems that an original maintenance platform needs to be fixed through bolts in a multi-point mode which causes trouble, and the maintenance platform can not applied to the disconnecting links with different models, can be solved.