Preservative agent box

The invention relates to a preservative agent box. The preservative agent box comprises an inner pipe, an outer pipe, an upper end cover and a lower end cover, wherein the inner pipe, the outer pipe,the upper end cover and the lower end cover jointly form an inner cavity; the preservative agent box further comprises a movable separation ring, a limit stop block and a separation film; the inner cavity is divided into an upper cavity and a lower cavity by the movable separation ring; the limit stop block is arranged on the inner peripheral wall of the outer pipe; the upper end and the lower endof the inner pipe are both communicating with the outside; the lower cavity is filled with preservative agent microspheres; the preservative agent microspheres comprise a wrapping layer, a preservative agent and a disintegrating agent; the inner pipe is provided with a water passing through hole; the separation film is arranged on the periphery of the inner pipe, and the upper end and the lower end of the separation film