Explicit Multi-Unicast (XCAST) is a complementary protocol of multicast thats support a very large number of small multicast sessions by specifies the destinations as the lust of unicast address explicitly.The usage of the IPv6 protocol creates new challenges such as the Quality of Service (QOS) mechanism that are currently supported for the internet Protocol version 6 (IPv6) in most implementations are fewer compared to IPv4 and in addition the whole network 's behavior is different.By considering IPv6 role in QoS and review the QoS routing mechanism using by multicast as well as unicast,this paper tries to investigate a proper model for Xcast QoS and proposes protocols on IPv6-based Xcast QoS.