Abstract: The cake product of the quick-open diaphragm filer press operated by Jiangzhuang Mine Coal Preparation Plant used to be high in moisture. To tackle this problem, while maintaining the mode of feeding from both ends, the following technical transformation work is made:shifting air compression mode to hydraulic mode, opening/sealing-up of holes on filter plates, holddown plates and thrust plates, addition of air-operated valves, corresponding pipes and compressed air accumulators and switching to angular air blowing and double-path air supply working modes. Practice shows that the use of the reformed press has led to reduction of the cake moisture from 26%~29% to 18%~21%, well up to the requirement for reduction of moisture of clean coal.