Abstract: The troubles with manual dosing of flocculating agent during filter pressing of coal slime involve slow dissolution rate and insufficient mixing of agent, and high labor intensity. To address this problem, an automatic agent dosing device is developed based on result of analysis of present operating status of filter press system. Practice shows that the device developed is capable of automatically executing agent adding process and making real-time and precise adjustment of agent dosage according to parameters of feed material, and its use can lead to reduction of waste of agent and labor intensity.