The invention discloses a combined-type power distribution cabinet pedestal, and the pedestal comprises pedestal frames which are made of two steel channels, wherein the openings of the two pedestal frames are opposite to each other. The front side walls of the two pedestal frames are connected with each other through a supporting beam therebetween, and the rear side walls of the two pedestal frames are connected with each other through a supporting beam therebetween. The supporting beams are formed through supporting beam branch bodies made of a plurality of steel channel segments, and connecting plates connected between each two adjacent supporting beam branch bodies. The top surfaces of the pedestal frames and the supporting beam branch bodies are respectively provided with a power distribution cabinet installation hole. The invention also discloses an installation operation method for the combined-type power distribution cabinet pedestal, and the method comprises the steps: enabling the pedestal frames, the supporting beam branch bodies and the connecting plates to be assembled; enabling a power distribution cabinet to be installed on the pedestal frames and the supporting beam branch bodies; enabling the power distribution cabinet pedestal and a power distribution cabinet on the pedestal to be moved to the ground of a cable well; enabling a cable to be connected to power distribution equipment in the power distribution cabinet, covering the bottom of the pedestal with concrete, arranging a circular isolation strip surrounding the concrete, keeping it grow naturally for ten days, and moving away the isolation strip after the concrete is solidified.