The invention relates to the field of thermal control boiler ancillary facilities and discloses a thermal control boiler steel shaft mounting method. The thermal control boiler steel shaft mounting method comprises the following steps that a, distances between layers of a boiler in the position where a steel shaft is arranged are measured, and the lengths of all hoisting sections of the steel shaft are designed; b, the hoisting sections of the steel shaft are connected and combined according to the design results; c, the assembled steel shaft is hoisted to a near position through a furnace top hoist or a winch, a first chain hoist is used for supporting, and a second chain hoist is used for adjustment, alignment and place taking of the elevation of the complete steel shaft; and d, alignment and place taking are conducted, and a shaft support and a cable support are welded. According to the thermal control boiler steel shaft mounting method, assembling is conducted on the ground, the construction difficulty is lowered, moderate construction is ensured, aloft work can be reduced, potential safety hazards are reduced, usage of scaffolds is reduced, and material cost is reduced; and meanwhile, construction progress is accelerated, the construction period can be shortened by 50% or more, and the labor cost is effectively reduced.