It is very difficult and important to treat Waste Activated Sludge. Above all, an effective process of Sludge Disintegration must be the key pretreatment, which will influence the effectiveness of the following treatment of Waste Activated Sludge directly. A Hydrodynamic cavitation system and two aerobic digestion reactor are made in the laboratory. The sludge from an MBR (Membrane Biologic Reactor) which has been treating sanitary waste are considered as the samples. Samplel were integrated by the Hydrodynamic cavitaion system, then it was put into the ADR (Aerobic Digestion Reactor)l; Sample 2 was put into the ADR2 directly. According to the physical model experiment work in the lab, the conclusions could be drawn, that as a pre-process, hydraulic cavitation method can make the sludge be dewatered easier, and accelerate the digestion reaction. After fifteen days of digestion process, the RR of cavitated sludge was 57%, which was higher than that of the sludge without cavitation treatment by 28%. In addition, the hydraulic cavitation device is simple, ready for industrialization, with higher utilization ration of energy and with little secondary pollution.