To improve mean-life and reliability of power cable, in this study, we have investigated electrical properties and stress-strain showing by changing the content of carbon black that is semiconductive additives for underground power transmission. Specimens were made of sheet form with the nine of specimens for measurement. Volume resistivity of specimens was measured by volume resistivity meter after 10 minutes in the pre-heated oven of both 25±1 [℃] and 90±1 [℃]. And stress-strain of specimens was measured by TENSOMETER 2000. A speed of measurement was 200[mm/min], ranges of stress and strain were 400[Kgf/㎠] and 600[%]. In addition tests of stress-strain were progressed by aging specimens in air oven. From this experimental results, volume resistivity was high according to increasing the content of carbon black. And yield stress was increased, while strain was decreased according to increasing the content of carbon black. And stress-strain were decreased some after aging because of oxidation reaction of chemical defect. We could know EEA was excellent more than other specimens from above experimental results.