The invention provides a cleaning agent and a cleaning method of a GGH heat exchange component applying the same. The cleaning agent comprises alkaline cleaning solution and acidic cleaning solution, wherein the alkaline cleaning solution contains 1.6 weight percent to 11.0 weight percent (wt, same below) of alkali, 0.7 to 2.4 of penetrating agent, 1.2 to 3.5 of scale dissolver, 0.3 to 1.2 of surfactant, 0.2 to 1.3 of remover b and the balance of water; and the acidic cleaning solution contains 2.6 to 5.5 of strong acid, 0.7 to 2.4 of penetrating agent, 0.3 to 1.2 of latent solvent, 0.2 to 0.6 of inhibitor, 0.2 to 1.3 of remover a, and the balance of water. The washing process comprises an alkaline cleaning step, an acid cleaning step and a high-pressure water flushing step between the alkaline cleaning step and the acid cleaning step. The cleaning process and the cleaning agent of the GHH heat exchange component have the advantages of quick and thorough cleaning, low cost, environmental protection, and the like.