The invention belongs to the technical field of oil and gas field reservoir reforming and particularly provides an online pulse plugging releasing method for a water injection well. The online pulse plugging releasing method for the water injection well includes the steps that a pulse source is assembled on the ground, the pulse source descends into an oil pipe in a pressure carrying mode to a down-hole target layer through a blowout control box and a blowout control pipe above a Christmas tree, and then the target layer is subjected to pulse plugging releasing in a casing pipe through depth correction. According to the online pulse plugging releasing method for the water injection well, reservoir plugging can be released deeply, injection pressure can be reduced, meanwhile, construction procedures are simplified, the construction period is shortened, the working efficiency is improved, and the construction cost is reduced.