As a network-based mobility management solution, Proxy Mobile IPv6 (PMIPv6) has been adopted by IETF, 3GPP and WiMAX to complement the host-based approach. In PMIPv6, the Local Mobility Anchor (LMA) is introduced to perform the mobility management and data forwarding, thus achieving the transparent mobility support. However, it results in the sub optimal routing path and single node failure. To realize the optimal routing and separate the forwarding function from the LMA, several routing optimization solutions have been proposed, but most of them are based on the MIPv6 built-in route optimization mechanism or MAGs tunnel, which incurs the additional overhead. In this paper, we propose a PMIPv6 route optimization solution based on the Identify/Location Split mechanism. Especially, in the proposed solution, a Location Identifier (LID) is assigned to each mobile node and mapped to its Home Network Prefix (HNP) to accomplish the optimal routing and reduce the additional tunnel overhead. The analytical results show that the proposed scheme is better than other schemes in terms of signaling cost, delivery cost and LMA service blocking probability.