A cationic polyelectrolyte with a high density charge, its average molecular weight was 2.60×10 6 and cationic character reached 45%, adsorbed on the particles with the adsorption pattern of static electricity gravitation between the cationic groups and the clay surface with negative charges. It could be neutralize the ζ potential of clay particle surface to 0 mV and keep with 0 mV, and make the capillary suction time of oily sludge reduce to 100～200 s and finally make it chemical destabilization, but also make the fine grains(diameter under 20 μm) be effectively flocculated and swept away. The flocculating reaction kinetics of cationic polyelectrolyte to solid particles of oily sludge was made certain as second order reactions.
