The invention discloses a method for erecting a steel truss beam by using a precast concrete cushion, comprising the following steps: S1, arranging a cushion stone on the top of a completed pier cap;2, providing a plurality of precast concrete pads, wherein that precast concrete pad is provide with a grouting hole, and the grouting hole extends to the bottom surface of the precast concrete pads;3, surrounding a plurality of that precast concrete pads on the periphery of the pad stone, wherein the precast concrete pads are flush with the upper surface of the pad stone, and two precast concrete pads adjacent to the precast concrete pads are fixed together; S4: Grouting into the grouting hole to fill the void between the precast concrete pad and the pier cap; S5: Hoisting the steel truss beam on the cushion stone, adjusting the steel truss beam to the designated position, installing the steel truss beam support, and removing and removing the precast concrete cushion. Compared with the steel cushion block method, the concrete used in the invention is not only safe in operation, but also saves a large amount of investment of the steel structure, and has good economy.