The aerobic and anaerobic cyclic activated sludge reactor of A/O process was separated into an A/O domestication segments and organic matter removal ability strengthen segments. In the A/O disposal system, organic carbon degradation, nitrogen and phosphorus removal from municipal waste water in reactor were investigated. Results showed that good performance of the A/O disposal system was achieved and the highest removal efficiencies of COD, TN and TP were 96%, 50% and 75%, respectively. When organic loadings varied from low to high, the removal ability increased and then the hybrid microbe in activated sludge degradation ability became strong. So the cyclic activated sludge was a useful method for eliminate organic matter removal from municipal waste water.