The invention discloses a wet-method preparation and activation method of nanometer calcium carbonate. Limestone is calcined and crushed, wherein a crusher is adopted for crushing, the crushed particle size is 1-2 cm, then limestone particles are put into a calcinator for calcining, calcining time is 120-360 min, temperature is 900 DEG C, in a calcining process, a fluidized bed is arranged in thecalcinator, and the limestone particles are subjected to fluidized calcining in the fluidized bed; quicklime is obtained, water is added, stirring is conducted to obtain slaked lime, and stirring is conducted for 30-60 min; the slaked lime is put into an activation reaction kettle, water adding is continued, meanwhile, heating is conducted for stirring, heating temperature is 45-65 DEG C, in an activation device, carbon dioxide is introduced for bubbling, and an activator is added while stirring to accelerate activation; wet calcium carbonate is obtained; after sedimentation and filtering areconducted, a filter press is used for filter pressing; the wet calcium carbonate subjected to press filtering is dried. The activation method has the advantages that the calcining speed is higher thanthat in the prior art, a calcining effect is good, and energy consumption is saved; the activation rate is improved.