The invention discloses a power transmission line composite insulator repairing support and a working method thereof. The power transmission line composite insulator repairing support comprises a supporting main body used for supporting repairing personnel. The supporting main body is in a plate shape, two ends of the supporting main body are respectively provided with a hanging mechanism, and the hanging mechanisms are hinged with end parts of the supporting main body. The invention further discloses the working method of the supporting main body. The repairing support has the advantages that the structure is simple, the assembling is convenient, the operation is simple, the repairing support is applicable to a tension-resistant composite insulator or a linear composite insulator and is applicable to the composite insulators of different models, the construction accords with human engineering, channels and working space through the composite insulator are provided to the repairing personnel, the repairing working mode is optimized, and the efficiency of the repairing work is improved.