In this study, PCBs in transformer oil samples have been analysed by using two methods which are the quick test performed with ion selective electrode and the gas chromatography with mass spectrometry detector (GC-MS). As results of quick test method, there are 61 oil samples in the total of 152 transformer oil samples have reached PCBs concentration (Aroclor 1260) over 50 ppm. These samples and adding to 14 other oil samples, having results of quick test method lower than 5ppm, have been analysed for PCBs by GC-MS method. At the threshold limit of PCBs in oil of 5 mg/kg, the study results have shown that the quick test method spends low expenses, saves time and has high reliability and precision data in two ranges of PCB concentration: under 5 ppm and upper 200 ppm (with R2≈ 0.95). However, PCB concentration in the range from 5 to 200 ppm could be detected by using GC-MS method after screening by the ion selective electrode method.