Abstract: With the micro-fine tailings in which the particle content of -20μm accounted for 90% as test object,the impact of the molecular weight and dosage of non-ionic flocculant on the settling performance of micro-fine tailings was studied.The results showed that with the increase in molecular of non-ionic flocculant,the settling velocity of tailings increased and the concentration of compression zone decreased.The affect of the flocculant dosage on the settlement of fine tailings is phased:at low dosage,the sedimentation rate is slow and the amplification is little;at moderate dosage,the sedimentation rate is fast and the amplification is large;at higher dosage,the sedimentation rate is basically stable and there is no significant increase;the concentrations of compression zone are decreased at first two stages and finally stable.When flocculant selection to be N1500 and the dose is 200g/t,a better settlement results of 5.46cm/min sedimentation rate and 38.46% compression zone concentration can be obtained.