The invention provides a combined framework pillar for a 500kV transformer substation and a mounting method of the combined framework pillar. The combined framework pillar comprises a framework main connector and framework legs, the same ends of two opposite supporting parts are fixedly connected to form the herringbone framework main connector, a cross supporting part is fixedly connected between the two supporting parts, the framework legs are fixedly connected with the two supporting parts respectively, a framework transition connector is arranged between two opposite framework legs, an end connecting plate is fixedly connected at the top of the framework main connector, and a mounting through hole is formed in the end connecting plate. The mounting method mainly includes the steps: pouring and wrapping by the aid of concrete on the mounting portions of the framework legs of the tail ends of the combined framework pillar to form concrete protection boots. In an integrated framework for the 500kV transformer substation, the assembly efficiency of the integrated framework is improved, resistant-lateral rigidity, wind load resistant and anti-shake requirements of the integrated framework can be met, and safe and reliable running of the 500kV transformer substation is ensured.