Manganese in water has low toxicity. The product will form the yellow stain when the industrial water content is high. There are many ways to monitor it. The determination of trace Manganese in the YangjiaoPu source water by oscillographic polarography is introduced in this paper. The result indicate that the standard deviation of this method is 0.001~0.002 mg/L, the relative standard deviation is 2.3~2.5% and the mark-on recovery ranged from 96.8%～105.8%. At the same time several problems needing attention about experiment process are posed in this paper.