The embodiment of the invention provides a power transmission cable connecting device and a wind generating set. The power transmission cable connecting device comprises a first assembly, a second assembly and a sliding electric connecting piece. The first assembly comprises a transmission part, a spacing part and a first conductive part, the first conductive part is fixedly connected with the spacing part, and one end of the transmission part is fixedly connected with the spacing part and used for driving the spacing part and the first conductive part to rotate around the axial direction of the first assembly. The second assembly comprises a second conductive part, and the second conductive part is opposite to the first conductive part along the axial direction of the first assembly. Oneend of the sliding electric connecting piece is fixedly and electrically connected with the first conductive part, and the other end is slidably and electrically connected with the second conductive part; or one end of the sliding electric connecting piece is fixedly and electrically connected with the second conductive part, and the other end of the sliding electric connecting piece is slidably and electrically connected with the first conductive part. According to the invention, a cable twisting phenomenon can be avoided.