The invention relates to a pickling method and a pickling device of low-temperature multi-effect sea water desalting equipment. The pickling method comprises the steps of rinsing with fresh water, pickling and rinsing with the fresh water again. A medium in the pickling step comprises 3-10% of sulfamic acid, 0.2-0.8% of corrosion inhibitor and a proper amount of defoaming agent and fresh water; the pickling temperature is 50-60 DEG C; and the sprinkle density of the pickling medium outside a heat exchange tube to be pickled is 0.03-0.05kg/(m2*s), and the pickling time is 6-8 hours. The pickling device utilizes a brine discharge pump of a traditional system as a pickling circulation pump, simplifies a pickling system, adopts the combined acidification equipment of a movable type pickling tank and is convenient for the pickling operation; and the pickling method adds a pickling inspection step after pickling, ensures the pickling effect, forms a favorable passivating film outside the pickled aluminium brass heat exchange tube by a passivation step, enhances the corrosion resistance of the heat exchange tube resisting sea water and strong brine and prolongs the service life of the heat exchange tube.