The invention belongs to the nuclear power plant reactivity control field and discloses a nuclear power plant end-of-life reactivity control method. The method includes the following steps that: (1) after a set is started, primary loop ammonia addition amount is controlled; (2) when the set operates normally, ammonia is added continuously; (3) the position of a tenth group of adjustment rods is adjusted at end of life; (4) a primary loop coolant purification system is adjusted, and alkali metal in a coolant is removed; (5) a primary loop boric acid storage and processing system is put into operation, and boron is removed; and (6) the pressure of a secondary loop is decreased. With the nuclear power plant end-of-life reactivity control method of the invention adopted, the reactivity of a reactor of a nuclear power plant can be controlled safely and effectively, and fuel consumption can be increased, and pollution can be reduced.