The invention provides a calculating method and a calculating system for bending rigidity of a connecting part of electrical equipment for a composite bushing. The method comprises the following steps: carrying out bending test on whole-column equipment and determining an elasticity modulus of the composite bushing according to a test result; carrying out bending test on single-section equipment on which a to-be-tested flange is located and determining the elasticity modulus of the to-be-tested flange according to the test result and the elasticity modulus of the composite bushing; determining the bending rigidity of the to-be-tested flange according to the elasticity modulus of the to-be-tested flange. According to the calculating method for the bending rigidity of the connecting part of the electrical equipment for the composite bushing, provided by the invention, by measuring the elasticity modulus of the composite bushing and the elasticity moduli of connecting flanges of all sections of composite bushing, the bending rigidities of cementing parts of the flanges for all sections of composite bushing are obtained, the numerical modeling accuracy of the equipment is favorably improved, and accurate data support is provided for evaluating mechanical properties of the electrical equipment.