In order to improve the safety, stability, and operational economy of the forced draft fans, performance tests were performed in the 600 MW power unit of Ningdong Power Generation Company. Based on the acquired test data, two retrofit schemes were proposed for the draft fans, including frequency conversion and operation at lower speed. According to the contrast results, the latter scheme was adopted finally. The test results after retrofitting showed that the efficiency of forced draft fans had been greatly improved, and very satisfactory energy-saving results were achieved.