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Gigabit-capable passive optical network (GPON) has been viewed as a promising technology for the next-generation FTTx optical systems because of the increasing demand for bandwidth. But the Dynamic Bandwidth Allocation (DBA) mechanism for multi-service Quality of Service (QoS) and Class of Service (CoS) is not specified; hence, for providing QoS and CoS, this paper introduces an adaptive priority scheduling integrated with Bi-partition Dynamic Bandwidth Allocation (APS-BDBA) mechanism to enhance the differentiated services over GPON. In the Inter-ONU scheduling, the B-DBA mechanism to divide the cycle time by partitioning the ONUs into two groups with some timing overlap to execute interleaved bandwidth allocation, and adjusts the bandwidth dynamically between the first group for high priorities T-CONT 1-2 and the second group for low priorities T-CONT 3-4 to eliminates the idle period problem and reduce bandwidth waste. In the Intra-ONU scheduling, we design an adaptive priority scheduling embedded in the ONUs, which will meet the minimum delay of highest priority traffic without sacrificing the low priority traffic bandwidth requirements. The scheduling is constructed by one System Queue (SQ), for T-CONT 1, and multi-Custom Queue (CQ), for T-CONT 2-4, when the congestion occurs, the CQ can be maintained in the application of the bandwidth in accordance with the ratio corresponding to DiffServ to improve CoS. The system performance of APS-BDBA is compared with the Jiang's protocol and DWFQ-MDBA in terms of the throughput, end-to-end delay and jitter in different proportion of traffic scenarios. The simulation results show that the proposed APS-BDBA over GPON can reduce the packet delay and packet delay variation for high priority traffic without sacrificing the low priority traffic performance to ensure QoS and CoS regardless the proportion of different traffic of subscribers.