Abstract: GC was applied to the determination of C₃H₈ and C₃H₆ in insulating oil with full vacuum degassing. The gases dissolved in the sample of insulating oil were separated from the sample by full vacuum degassing technology. The analytes were separated on Propack Q chromatographic column and 5A molecular sieve chromatographic column, and detected by FID. Linear relationships between values of peak area and volume fraction of C₃H₈ and C₃H₆ were kept in definite ranges, with detection limits of 0.33, 0.29 μL·L^-1, respectively. On the base of blank sample, test for recovery was made by standard addition method; values of recovery of C₃H₈ and C₃H₆ were in the ranges of 92.1%-106% and 94.3%-108%, respectively. The proposed method was applied to the analysis of samples of insulating oil, giving values of RSDs (n=6) of C₃H₈ and C₃H₆ of 6.8% and 3.2%, respectively.