Abstract: In order to find out the factors underlying the low efficiency and high energy consumption of the plant's coal pulverizing system and make it possible to operate efficiently in an energy-saving manner, test is made with the samples collected through opening holes on the MPS vertical spindle pulverizer. Test result indicates that the proportion of the circulating load in the material to be ground is up to 90% and its ash is 20 percentage points higher than that of raw coal. Tests on milling of mixed materials is also conducted for analyzing through simulation the effect of circulating load and its control on breaking behavior of coarse particles and the energy consumption involved. As evidenced by test result, with decrease of proportion and ash of finer particles in material bed, more specific energy can be distributed to the crushing of coarser particles, raising as a result the efficiency of the energy in crushing operation. Based on the result of numerical simulation and analysis of sampling data, the effect of airflow velocity, angle of baffle plate and hydraulic loading force on separation efficiency and internal flow field has been brought to light. It is proposed to change part of high-density minerals to stone-like coal for discharge as rejects for improvement of milling environment, increase of crushing and sizing efficiency and reduction of energy consumption.