The invention provides a method for repairing an insulating support and a protective cover of a metro contact rail. The repairing method comprises the following steps that A1, a pneumatic angle grinder is used for grinding the surface of a detection sample; A2, the surface of the detection sample is cleaned by using compressed air; A3, the surface of the detection sample is cleaned by using acetone; and A4, paint spraying treatment is carried out on the surface of the detection sample. The invention further provides a method for detecting the influence of repairing of the insulating support and the protective cover of the metro contact rail on product quality.