The invention discloses a construction method of a large full-steel-structure-type intercooling tower. The construction method comprises the following steps of assembly of triangular supports and broadening platforms, pre-mounting of peripheral guard plates, mounting of a lower cone section and the broadening platforms, mounting of the two sets of triangular supports of the lower cone section andrib plates between the two sets of broadening platforms, mounting of an upper cylinder section and complete mounting of guard aluminum plates of the upper cylinder section, and mounting of rib platesbetween the two sets of triangular supports of the upper cylinder section. Through the construction method, construction of the full-steel-structure-type intercooling tower can be achieved.