Abstract: In order to reduce the moisture of flotation concentrate filter cake and accelerate the cake formation speed, non-ionic polyacrylamide (PAM) with molecular weight of 7 million and non-ionic surfactant (L-64) were selected and dewatering tests were carried out in a laboratory pressurized filtration system using dosing methods such as separate addition and mixed addition. The mechanism of enhanced dewatering by compound dosing was investigated by contact angle measurement, infrared spectroscopy, surface tension of the filtrate and floc morphology observation. he results show that PAM can accelerate the dewatering speed but the effect of water reduction is average, L-64 can obviously reduce the moisture of fine coal but the filtration speed is average; the compound addition of chemicals can effec-tively reduce the cake formation time and reduce the moisture of filter cake, under the same amount of chemicals added, adding PAM first and then L-64 is more beneficial to reduce the moisture of filter cake, and adding L-64 first and then PAM is more beneficial to reduce the cake formation time. The paper proposes a dual objective dewatering efficiency enhancement level evaluation model based on filter cake moisture and cake formation rate, and gives the optimal dosage of compound chemicals. The compound dosing can improve the hydrophobicity of coal surface, reduce the surface tension of filtrate, and form a floc structure with good looseness and permeability, which is conducive to the removal of capillary water between coal particles, with the dual effect of reducing the moisture of filter cake and improving the filtration speed.