The invention discloses a distance back-up protection setting method of an ultrahigh voltage circuit. The distance back-up protection setting method of the ultrahigh voltage circuit comprises the following steps of: (1) carrying out three-section configuration on grounding distance spare protection and phase-to-phase distance protection respectively; and enabling each section of the grounding distance spare protection and the corresponding section of the phase-to-phase distance protection to use the same constant value; (2) setting the I section of the grounding distance spare protection by reliably avoiding metal faults occurring outside an area, so as to obtain a constant value of the I section of the grounding distance spare protection and a constant value of the I section of the phase-to-phase distance protection; (3) dividing the setting of the II section and the III section of distance spare protection into the setting of the II section or the III section of standard side distance spare protection and the setting of the II section or the III section of non-standard side distance spare protection according to a datum mark, so as to respectively obtain the constant value of the III section of the grounding distance spare protection and the constant value of the III section of the phase-to-phase distance spare protection. On the premise of not reducing security risk of a power grid, the adaptation capability of a spare protection constant value to an operation manner of the power grid is improved, and the working capacity of setting calculation is greatly reduced.