With pH, MLSS, MLVSS, TU, SCOD and DD as evaluating index, the effectiveness of disruption of excess sludge with choking cavitation was researched experimentally, and the flow, back pressure and disruption time on the disrupting effects were investigated to seek the optimal structure parameter and hydraulic parameter. Results indicate that choking cavitation is an effective method for disruption of the excess sludge. After the excess sludge disrupting, MLSS and MLVSS reduce, SCOD and TU rise, and pH has little change. The disrupting ability is enhanced with the increase of flow, and with the back pressure increasing, it firstly enhanced and then weakened；The better operating condition is the flow of 1.273 0 m3/h and the back pressure of 238.45 kPa. Under this condition DD is up to 13.249% after looping 10 times.