The utility model discloses a power battery module and a wiring harness fixing device thereof. The wiring harness fixing device comprises a body and an elastic buckle part, wherein a wiring channel is formed in the body; the wiring channel penetrates through the body along the length direction of the body; the elastic buckle part is arranged on the outer part of the body; and the elastic buckle part comprises a blocking hook used for blocking the body on the power battery module. The wiring harness fixing device of the power battery module in the embodiment of the utility model is simple in structure, convenient to dismount, capable of being repeatedly used, and firm in wiring harness fixation.