Polymer nano-microsphere blocking agent and preparation method thereof

The invention discloses a polymer nano-microsphere blocking agent and a preparation method thereof. The preparation method comprises the following steps: uniformly mixing white oil, a hydrophilic group surfactant and sorbitan fatty acid ester to obtain an oil phase; the preparation method comprises the following steps: dissolving acrylamide, acrylic acid, a salt-tolerant monomer and divinyl benzene in water to obtain a first water phase; the second water phase is a sodium hydroxide solution; adjusting the pH of the first water phase to 7 by using the second water phase to obtain a third water phase; and under continuous stirring, adding the first initiator into the oil phase, adding the third water phase, emulsifying at 20-25 DEG C for 3-7 minutes, introducing nitrogen for 5-10 minutes, adding the second initiator, heating to react for 2-3 hours, cooling and discharging to obtain the polymer nano-microsphere blocking agent. The polymer nano-microsphere plugging agent disclosed by the invention is a salt-toler