[Show abstract][Hide abstract] ABSTRACT: In this paper, we studied on life-decision of underground cable of live-lines state. As all equipments have been expected life, underground cables decided design-life on the whole 30 years because underground cable have been occurred aging as time goes. CV cable has been become about 30 years after installation in the South Korea, is come to the important point of time with estimation about life. Study target cable is 22 kV CV cables in this point of view and installation cable is about 10 years before and behind. Measurement method used DC leakage method of live-lines state that applied voltage of 50 V in neutral point and data is analyzing result that is measured during 5 years. In this result, insulation resistance could confirm that change according to season and cause is effect of humidity, seasons and load current. Also, reduction of insulation resistance by Weibull distribution could confirm. As a result, the aging speed of cable that water tree is gone could confirm very fastness. Numerical analysis result, cable that water tree is not gone could confirm that life of cable that has passed 10 years remains about 10-20 years.