Abstract: Both turbidity monitoring and particle counting technique are applied to evaluate particle removal effect of filtered water within full ranges of particle size by potassium permanganate composite preoxidation process in pilot scale.The results show that the particle removal effect of filtered water can be enhanced effec- tively by preoxidation of potassium permanganate composite.The reduction of total particle number is reached 65.0%.The quality variations of filtered water can not be indicated by index of turbidity.The removal per- formances of particle matters of filter are indicated effectively by the combined application of turbidity and par- ticle counting technique.