The invention discloses a thermal insulation wall thickness adjusting method for a thermal insulation shelf used for special (ultra) high voltage electric reactor mounting in an alpine region and relates to the technical field of power equipment mounting in alpine regions. The method reduces thermal insulation shelf construction cost at the same time of enabling the thermal insulation shelf to meet thermal insulation requirements. The method includes obtaining the heating power P of a heater and a unit time heat dissipation volume qd of the ground in the thermal insulation shelf so as determine the unit time heat dissipation volume qt of the shelf body of the thermal insulation shelf and further determine the thickness of a thermal insulation wall according to related heat conduction parameters of the thermal insulation wall. The method provided by the invention is used for determining the wall thickness of the thermal insulation shelf when constructing the thermal insulation shelf used for special (ultra) high voltage electric reactor mounting in the alpine region.