Abstract: The flotation feed containing a high proportion of high-ash fine coal(for use as coking blend after treatment) is taken as the object to explore the influence of high-intensity pulp preconditioning on high-ash fine coal flotation effect. Based on result of size analysis of the feed, the influence of ash of flotation concentrate of each size fraction under different pulp conditioning intensities and the pattern of change of hydrophobicity of coal under the effect of high-intensity pulp conditioning are investigated through test on contact angle and flotation experiments. As revealed by study results, high-intensity pulp conditioning can lead to increase of contact angle of low-ash fine particles as a result of increase of ultrafine particle-flotation agent collision probability, promotion of floating-up of medium-and low-ash fine particles and inhibition of nonselective floating of high-ash fine particles, hence making it possible to increase recovery of combustible matter, reduce ash of concentrate and improve flotation efficiency.