Abstract: H~# as quench indicator, with help of triple-label proceeding computer program, ~3H, ~(14)C, and ~(125)I triple label determination and calculation method was established on well crystal detector and liqid scintillation detecting system. At the same time, the effects of various quenching, different ~3H, ~(14)C, ~125)I activities and activity ratios on cal culated errors were observed. The results showed that the calculated errors were below 10％ when H~#<227 and nuclidic activities were relatively lower. The advantages of this method are as following: simple operating, quick result and the metabolism of three substances which are labeled distinguishly with ~3H, ~(14)C, and~(125)I may be observed at the same sample and same time.