Abstract: According to the features of high varied coal quality in the large coal preparation plant, a XJM-S28 mode floatator was researched and developed.The mi ddlings container flexible with a primary floatation and secondary floatation technique could be applied to improve the suitable ability of the fine coal floataiity.The XJ M-S28 mode floatator would have a mechanical mixing and self- breathing mode, low power consumption floatation, good air inflation effect and others. The key paramet ers of the large floatator were determined with a simulation enlargement method.The floatator could be applied to a coking coal preparation plant with a production capa city of 3750 000 tons per year.In comparison with previous used WPF mode micro-bubble floatator, the clean coal production of the new floatator could be increased wi th 107 700 tons per year and the electric power consumption could be saved with 1 068 700 kW.h per year.