This study was conducted to identify the viability of Bacillus thuringiensis bacterial on a bio-degradation process for Kirkuk light crude oil. The viable count of Bacillus thuringiensis showed great capability on the biodegradation of crude oil. These bacteria exhibit the ability to dismantle crude oil through clear emulsion layer of crude oil. And they have a good efficiency to dismantle hydrocarbon compounds by 80%, and total biomass reaches to 5 g/l, while the amount of emulsion reaches to 2.3 g/l. For more evidences on the biodegradation action of Bacillus thuringiensis which have been supported by using the technology of gas-Chromatography which confirms the occurring of biodegradation process. The visual examination of gas-Chromatography shows the disappearance of a number of chemicals, as well as decrease in peak area for some material.