The invention discloses a monorail contact line abrasion detecting device and method, relates to an urban railway transit technology and aims at providing a device and method for continuously performing monorail contact line abrasion detection. According to the technical key point, the monorail contact line abrasion detecting device comprises two supports, two contact line image acquisition modules and a data processing unit, wherein one end of the first support is fixed to a detection vehicle, the other end of the first support extends to the lower portion of the right side of the detection vehicle from the right side of the detection vehicle, and the first contact line image acquisition module is installed at the other end of the first support. One end of the second support is fixed to the detection vehicle, the other end of the second support extends to the lower portion of the left side of the detection vehicle from the left side of the detection vehicle, and the second contact line image acquisition module is installed at the other end of the second support. The data processing unit is used for receiving left side and right side contact line image data output by the two contact line image acquisition modules and calculating the abrasion proportions of contact lines according to the contact line image data.