The QoS management is an agreement of service user and service provider in B3G networks, and service provider must support proper the network service to service users by the agreement facts. The service provider must provide the QoS method to maintain the agreed service, which manages the detail method of system level from policy level. By the agreement of service policy, the service provider can give the QoS to the service customer with the service agreement. Hence, in this paper we propose a QoS mapping method of heterogeneous networks to provide the customer service through the service agreement based on the SLA of B3G networks.