The invention relates to a transformer substation flexible circuit conductor blanking length numerical solution method based on catenary. A transformer substation flexible circuit conductor is divided into a strain insulator string and a flexible bus, structural parameters and material parameters are determined, the hitch point of the strain insulator string serves as an origin, a X-Y coordinate system is established, and an analysis model of transformer substation flexible circuit conductor blanking length is established; secondly, a sag step length dichotomy adjustment module is constructed; thirdly, a horizontal stress calculation adjustment module is established; fourthly, a hardware space coordinate calculation module is established; fifthly, a total sag calculation error adjustment module is established; finally, the calculation of modules is combined, and the blanking length of the flexible circuit conductor can be obtained. On the basis of the known structural parameters and material parameters, stress is obtained by using sag, designed sag serves as a limiting condition, by means of a numerical method, accurate sag, horizontal stress and the like are obtained, the accurate flexible circuit conductor blanking length is obtained, and the transformer substation flexible circuit conductor blanking length numerical solution method has very high application value.