Abstract: The size distribution characteristics,Zeta potential and ρ(SS) of superfine particles in the drainage pipe network of a mountainous city were investigated.The chemical parameters of the wastewater,such as electric conductivity and pH,were also analyzed.The results showed that particle size,Zeta potential,ρ(SS) and conductivity ranged from 21.04-73.53 μm,-20.83--11.15 mV,106-492 mg/L,and 973-2445 μS/cm,respectively.The average values of these parameters were(43.74±14.12)μm,(-17.95±1.88)mV,(233±90)mg/L,and(1343±331)μS/cm,respectively.The pH ranged from 7.25 to 7.63.According to the results,industrial wastewater had a significant and regular impact on the size distribution and Zeta potential of superfine particles in the drainage pipe network.In addition,superfine particles could be directly carried into biological treatment systems because of the limited removal ability of the traditional grit chamber on superfine particles.