The invention discloses a middle-deep well plugging method by adopting a deferrable water swelling plugging agent. The middle-deep well plugging method comprises the sequential steps that (1) a plugging agent matched with the leakage rate of a leakage section is prepared; (2) pulping base liquid with the viscosity of 40 s to 55 s is prepared; (3) the plugging agent is added into the pulping base liquid and stirred and mixed evenly, and sodium hydroxide is added to adjust the pH of 10-11 to obtain a plugging slurry; (4) according to the principle of small displacement pump in and large displacement replacement, the plugging slurry is quickly driven into a leakage section stratum; (5) the method of circulation pressing or shut in and pressure building is adopted, and thus the plugging slurrycompletely enters a leakage layer; and (6) pulling out of hole is conducted to a safe well section for static plugging for a period time, and the plugging construction is completed. According to theplugging method, the deferrable water swelling plugging agent is correspondingly applied to the plugging construction of the leakage stratum with different leakage rates, the situation that the deferrable water swelling plugging agent is completely pumped into the leakage stratum gap and not prone to leakage is ensured, and the effect of deferrable swelling and plugging of the deferrable water swelling plugging agent is effectively played.