A fiber optic insulator comprising a mandrel, an optical fiber and an insulating collar, wherein the two ends of the mandrel are respectively provided with a high-voltage end fitting and a low-voltageend fitting, and the outer end of the high-voltage end fitting is connected with the insulating collar. A portion of the mandrel between the high-voltage end fitting and the low-voltage end fitting is provided with an umbrella skirt, and the inside of the low- voltage end fitting is provided with a pigtail on the optical fiber, and the pigtail extends to the outside of the low- voltage end fitting. The mandrel is composed of glass fibers, and the center of the mandrel is provided with an optical fiber including a grating covering area and a pigtail. The fiber optic insulator not only can realize on-line monitoring of mechanical and electrical properties of the composite insulator, has good mechanical performance, and saves production cost and improves manufacturing efficiency.