Traditionally,decayed ancient timber columns are stabilized using the “Dunjie” method, which involves wrapping the column with iron bands. To test the validity of the method, a timber column from an ancient building in the Forbidden City was selected as example for research. Four models were built, some of which had decayed bottoms, and were strengthened by iron bands according to the Dunjie method. Axial compression tests were carried out. Parameters such as forcedisplacement curves, ductility, strain and vertical stiffness of the models were obtained to test the results.The mechanism of strengthening by the Dunjie method was also considered. The results show that the ultimate compression strength of the strengthened columns can be restored to about 91.8% that of the undecayed column, their ductility can be restored to about 95.2%, and their compressive strain can be restored to about 97.2% in horizontal direction and 84.1% in vertical direction. The vertical stiffness values of the strengthened columns are larger than that of the unreinforced, undecayed column. So far as integrity is concerned, the strengthened columns are not as good as the undecayed column because of the difference in strength between iron and timber. Thus the strengthening capability of the traditional Dunjie method is limited.