The invention relates to a water plugging agent and a preparation method thereof. The water plugging agent comprises the following components in parts by weight: 100 to 120 parts of
acrylamide, 60 to 100 parts of a strength
monomer, 10 to 20 parts of a high-adhesion promoting
monomer, 0.01 to 0.1 part of a micro-crosslinking agent, 1 to 4 parts of an associative thickener, 40 to 80 parts of a response
monomer, 2 to 6 parts of an associative monomer, 0 to 27 parts of
potassium hydroxide, 320 to 400 parts of water, 200 to 280 parts of an oily
solvent, 20 to 40 parts of an emulsifier, 2 to 5 parts of a co-emulsifier, 1 to 5 parts of a
polymerization stabilizer, 0.02 to 0.5 part of an initiator and 25 to 35 parts of a
phase inversion agent. The water plugging agent disclosed by the invention is of a micro-crosslinking association
network structure, mainly adopts intermolecular crosslinking, has dense grid holes, thick molecular chains, strong water molecule wrapping capacity, more stable gel and lower
dehydration rate, can effectively reduce the permeability of a
rock core, and has a good plugging effect.