The aging fracture accident of composite insulator rod seriously affects the stability of power system operation. In order to study the aging fracture of the composite insulator rod, the fracture characteristics and aging characteristics of the composite insulator rod are analyzed, and the aging fracture mathematical model of the composite insulator rod is summarized. Secondly, the unknown parameters in the mathematical model are measured by the aging fracture test of the composite insulator mandrel, and the aging rate of the composite insulator mandrel under different working con-ditions is determined. Finally, by designing the aging fracture mathematical model verification test, the test results are compared with the calculation results of the mathematical model to verify the accuracy of the aging fracture math-ematical model. The results show that the Young’s modulus of the composite insulator rod will decrease continuously when the aging corrosion reaction occurs, and the value of the aging reaction rate constant is calculated by the change of Young’s modulus. The effect of brine on the aging of composite insulator rod is very weak, while the effect of water and nitric acid on its aging is more serious, and the electric field has an accelerating effect on the aging reaction. The crack propagation rate calculated by the mathematical model of aging fracture of composite insulators is roughly consistent with that obtained in the test. The conclusions can provide theoretical support for the aging diagnosis of composite insulator rod.