The invention discloses an insulator angle detection system based on a color mark sensor. The system comprises a slide glass, the color mark sensor and a PLC (programmable logic controller), the slideglass is mounted on outer surface of an insulator, a section identification is arranged on the slide glass and includes an A segment identifier, a B segment identifier and a C segment identifier which are sequentially arranged, colors of the A segment identifier, the B segment identifier and the C segment identifier are different from the color of the slide glass, the color mark sensor is positioned on one side of the slide glass with the section identification, middle section identifications have same widths, the width of the A segment identifier is gradually reduced relative to that of theB segment identifier, the width of the C segment identifier is gradually increased relative to that of the B segment identifier, and the output end of the color mark sensor is connected into the PLC.The insulator angle detection system has the advantages of timeliness and accuracy in detection, simplicity in mounting, low cost, convenience in use and easiness in maintenance.