Abstract: The pore structure of filter cake is the key factor influencing coal slurry water filtering effect,but filter cake structure is easily damaged and coal particles and pores become indistinguishable during the coal slime filter cake measurement.In order to study the pore structure characteristics of filter cake in coal slurry water pressure filtration,this paper established a coal slime filter cake solidification device and method.Effect of -0.074 mm particles content and filtration pressure on coal slime filter cake pore structure were investigated using polarizing microscope.The results show that an increasing amount of -0.074 mm particles content results in smaller decreasing rate of pore diameter,pore area and porosity,narrower pore diameter distribution,and larger proportion of small pores in the constituents of porosity.It also leads to increasing fractal dimension of filter cake pore section edge,more zigzag pore section edge and more complicated pore structure.Increase in coal slime water filtration pressure prior compresses filter cake large pores.As the filtration pressure rises,filter cake pore compresses,porosity descends and fractal dimension of pore section edge ascends.In addition,it complicates the pore structure with more zigzag pore section edge and more irregular pore shape.