The utility model discloses a visual inspection device for a diamond wire. The device comprises a stable guide part and a visual detection part, the visual detection part comprises two supports with universal self-locking wheels at the bottoms, a first linear guide rail is horizontally arranged between the supports and connected with one end of a connecting rod, an air cylinder is fixed to the other end of the connecting rod, a CCD camera is arranged on a piston rod of the air cylinder, a sliding rod is further arranged between the supports, and the sliding rod is sleeved with a light source.The stable guide part comprises a mounting plate supported by a supporting column, a tensioning wheel, a wiping part and a stable guide wheel are sequentially arranged on the mounting plate, and the diamond wire sequentially bypasses the tensioning wheel, the wiping part and the stable guide wheel; according to the utility model, the quality of the diamond wire can be detected without difference,the diamond wire can be simply wiped before detection, the tightness degree of the diamond wire can be adjusted at any time during detection, a light source is uniform, shadows do not exist, the detection result is reliable, and the detection quality difference of the diamond wire can be reduced.