Abstract: To improve the beam intensity and filament service life-time of model 358 duoplasmatron ion source for GIC4117 tandem accelerator at Beijing Normal University, the proportion of Ba, Sr and Ca elements in ion source filament coating material, filament coating method and protection measure of ion source were improved. The effects of intake, arc current and constrained magnet current on the ion source output beam intensity were discussed under different filament currents. The accumulated life-time of the filament reaches over 200 h, and the beam intensity in the target chamber is about 500 times higher than that of the original 860A sputtering source. At the same time, the abnormal arc breaking in the debugging process of model 358 duoplasmatron ion source was analyzed and improved.