The application discloses a wastewater treatment device and a working method thereof. The device comprises a water storagepool, a movable base movably connected to the water storagepool, a moving unit and a particle throwing unit arranged on the movable base, a solution throwing unit arranged on the particle throwing unit, and a measuring unit connected to the solution throwing unit. The device can avoid the concentration of a certain area being too high to reduce the dissolution speed of the medicament, and the blades on the crushing rollers of the collecting assembly can also have a mixing effect, thereby accelerating the dissolution speed of the medicament.