In the present communication, four particle size fractions, namely 0.500-0.250 mm, 0.250-0.125 mm, 0.125-0.074 mm, and 0.074-0.045 mm, were conducted to investigate the effect of particle size on the hydrophobicity characterization of low-rank coal surfaces using induction time instrument. To reduce the heterogeneity effect of low-rank coal on hydrophobicity during induction time measurements, experimental coal samples with low ash content and a percent attachment parameter were adopted. X-ray photoelectron spectrometer results demonstrated that after the grinding process, the content change in hydrophilic and hydrophobic functional groups played a small effect on the hydrophobicity of low-rank coal samples during the induction time measurements. Moreover, the steepness of percent attachment vs. induction time curve demonstrated that particle size played a greater effect on induction time. Furthermore, the induction time is sensitive to low-rank coal particle sizes ranging from 0.250 mm to 0.074 mm.