Abstract: Power cable plays an important role in power transmission in substation. Line grounding and equipment damage caused by low voltage side of main transformer and bus contact cable defects will lead to serious losses. The hidden danger inspection caused by a 10 kV bus contact cable failure event was introduced. Through appearance inspection and insulation test, a number of hidden dangers were found, the causes of hidden dangers were analyzed, the treatment process was introduced, and suggestions for prevention and improvement were put forward. The results provide reference and application examples for the prevention and treatment of cable defects in substation.