In order to efficiently exploit high performance network, researchers have developed many user-level protocols, which can achieve high bandwidth and low latency the bottom hardware supplies. But user-level protocols supply a completely different API, which makes them only support science computing, and traditional Socket-based network application program with kernel-level protocol cannot run on them. To solve this problem, a IP supporting module has been implemented on user-level protocol BCL-3, which makes it support both science computing and existing TCP/IP-based network application programs efficiently. And based on software overhead analysis of TCP/IP, BCL-3 adopts some optimization in IP supporting module, which makes TCP/IP over BCL-3 achieve high performance. The improved BCL-3 has been run on Dawning3000L super server. On Dawning3000L, TCP/IP over BCL-3 has achieved performance with maximum bandwidth of 938Mbps and minimum one-way latency of 48.1μs.