The invention discloses a mounting structure of a disc-type electric cabinet for a low-floor vehicle and belongs to the technical field of rail transit mounting. The electric cabinet is mounted in a transition area between a vehicle roof and a vehicle window. Various electrical devices are mounted on the structure. A cabinet body of the electric cabinet comprises a plurality of sealed tubular cavity structures, and the multiple sealed tubular cavity structures are axially connected through a splicing plate and then form a long and narrow tubular cavity structure stretching across the window area of a vehicle body. The upper portion of the long and narrow tubular cavity structure is provided with a bending part, the bending part is connected with the vehicle roof through bolt fasteners, and the lower portion of the long and narrow tubular cavity structure is connected with a vehicle body stand column through a support. According to the mounting structure of the electric cabinet, residual space of the vehicle roof of the low-floor vehicle is effectively used, the mounting structure is well linked with an external maintenance interface, and equipment mounting and equipment maintenance are facilitated due to reasonable longitudinal-depth arrangement.