Abstract: With the deepening of the national energy conservation and emissions reduction work，it is necessary for the coalfired power plants to have several retrofits to meet the standard． As a result，the flue gas system resistance increases，and the original induced draft fan units need to be modified． The study of the modification strategy for the induced draft fan showed that the scheme of combining of the original induced draft fans with the booster fans was the better one，and the selection of the fans should be based on the consideration of the plant site，the project schedule，the economical efficiency of investment and operation．