In this paper, we identified an important issue when supporting a large scale networked virtual environment(NVE) with a server cluster. This issue is similar to the process migration issue on the parallel computing study and we refer it as the avatar migration problem. That is, when an avatar of an NVE is moving from one region managed by a server to another region managed by a different server, the client site may perceive abrupt screen change due to the different contents managed by these two servers. This paper proposes equations to solve this problem and elaborates the proposed avatar migration mechanism with state diagrams. The implementing architecture is also given in this paper. Our experiments that successfully show the efficiency of the proposed mechanism are given at the last.