Abstract: For the situation of many services in the users' request,the paper introduces DBA algorithm in EPON upstream channel in support of QoS. We propose two control frames and two novel DBA algorithms supporting multi-priority services with differentiated QoS:SGMTA algorithm based on ONU and MGSTA algorithm based on OLT. In our conducted simulation experiments, both algorithm show satisfied delay performance and stable buffer size as the network load increases. Thus, we conclude that these two novel DBA algorithms are reasonable and practical in support of multi-priority EPON system.