The invention provides a dosing device and a using method thereof. The invention relates to the dosing device which mainly comprises a stock bin and a preparation tank; the dosing device is characterized in that a spiral feeder and a fan are arranged under the stock bin; the stock bin is connected with the preparation tank by a pipeline; the preparation tank is connected with a water inlet pipe; the preparation tank is connected with a storage tank. When the dosing device is used, a vibrator arranged outside a powder storage tank intensively shakes, so that discharging is conveniently carried out, and the residue of discharging is less; the powder storage tank is better in airtightness, so that the dust is reduced; the powder in the powder storage tank is pushed out by the spiral feeder, is sent into the preparation tank by the fan and is mixed with water. After the improved device is used, the equipment failure rate is remarkably reduced, the running stability of a mechanical concentration machine room is improved, the ambient environment of the dosing device is improved, the work load of maintenance and management can be greatly reduced, the operating efficiency is increased, the agent loss caused by equipment failure is reduced, the cost is lowered, and obvious economic benefit can be obtained.