The invention discloses a gas-fired boiler coal economizer which comprises a U-shaped coal economizer pipe. Steering headers are arranged at the two ends of the coal economizer pipe correspondingly. A hand hole door is arranged on one of the steering headers. A rear pipe plate, a middle supporting plate and a front pipe plate are sequentially arranged under the coal economizer pipe at intervals. Backing rings used for fastening the coal economizer pipe are arranged between the rear pipe plate and the coal economizer pipe. Fastening rings used for fastening the coal economizer pipe are arranged between the front pipe plate and the coal economizer pipe. By the adoption of the U-shaped coal economizer pipe, the heat exchange area of the coal economizer pipe can be increased, the heat exchange efficiency of the coal economizer pipe can be improved, arrangement of the coal economizer pipe is facilitated, and the structure of the coal economizer is simplified. During installation, the coal economizer can be installed only by fixing the rear pipe plate, the middle supporting plate and the front pipe plate, and convenience is achieved.