The present invention provides a hot-line cleaning robot for high-voltage/ultra-high-voltage transmission line insulators and a use method thereof. The hot-line cleaning robot comprises two end rings formed by hinging one end of a 240-degree ring (1) and one end of a 120-degree ring (9) and buckling the other ends of the same; traveling racks (16) are arranged on inner circles of the end rings; two ends of two guide rail fixing frames (7) are respectively mounted on two 240-degree rings (1) through radially arranged adjusting bolts (4); two ends of one guide rail fixing frame (7) are respectively mounted on the 120-degree ring (9) through the radially arranged adjusting bolts (4); three cleaning devices (2) are mounted on the end rings provided with the traveling racks (16), and the three cleaning devices (2) and the three guide rail fixing frames (7) are arranged alternately; a linear guide rail (6) and a linear guide rail motor (15) for driving the linear guide rail (6) to rotate are axially arranged on each guide rail fixing frame (7); a lower layer steering gear (10) and an upper layer steering gear (11) are arranged on each linear guide rail (6); and fixing rods (13) are arranged on the lower layer steering gear (10) and the upper layer steering gear (11). The present invention has the advantages of strong universality, wide adaptation range and high safety.