Abstract: Based on the huge number of current locomotive cables, there are many over-age or old supporting cables and systems, how to accurately assess the service life of locomotive cables has become a common problem. In the paper, relationship between oxidation induction temperature and relative elongation at break retention of polyolefin material of locomotive cable insulation layer at different aging temperatures, and changing trend of FTIR infrared spectrum during the aging process at different temperatures, were studied. Results showed as the aging process deepened, relative elongation at break retention gradually decreased, as well as oxidation induction temperature. Trend of FTIR infrared spectrum provided a screening basis for the selection of high temperature points in life evaluation of cables. Tests of oxidation induction temperature and FTIR infrared spectrum could be used as auxiliary analysis means for life evaluation of cables. It could provide an effective reference for the selection of high temperature point and thermal aging monitoring of cables.