The invention relates to a pipe support connecting device fast to disassemble and assemble. By adoption of the connecting device, connection of C-type steel supports can be effectively achieved. According to the technical scheme, the pipe support connecting device comprises two pieces of inward flanging C-type steel, and a disassembling and assembling type connecting piece mounted on the inward flanging C-type steel. The disassembling and assembling type connecting piece comprises closure nuts, screws and a cover plate. Each screw comprises a clamping head, a square positioning column perpendicularly arranged on the clamping head, a middle column perpendicularly arranged on the square positioning column, and a threaded column perpendicularly arranged on the middle column. The cover plate is clamped onto two curled edges of each piece of inward flanging C-type steel. A through hole is formed in the position, arranged between the two curled edges of each piece of inward flanging C-type steel, of the cover plate. Each clamping head is located between two flange plates located below corresponding flangings of the corresponding piece of inward flanging C-type steel. Each closure nut is screwed on the corresponding threaded column and used for pressing the cover plate tightly. Each screw is rotated, a corresponding gasket is driven to rotate simultaneously; and when each gasket is rotated, the corresponding screw is driven to rotate simultaneously. The pipe support connecting device fast to disassemble and assemble is easy to produce and operate; pipe supports can be fast disassembled and assembled, the labor hour is greatly shortened, and the efficiency is improved; and the pipe support connecting device fast to disassemble and assemble is safe, reliable, convenient to use, and good in effect.