  In this letter, we propose a new routing strategy to improve the
transportation efficiency on complex networks. Instead of using the routing
strategy for shortest path, we give a generalized routing algorithm to find the
so-called {\it efficient path}, which considers the possible congestion in the
nodes along actual paths. Since the nodes with largest degree are very
susceptible to traffic congestion, an effective way to improve traffic and
control congestion, as our new strategy, can be as redistributing traffic load
in central nodes to other non-central nodes. Simulation results indicate that
the network capability in processing traffic is improved more than 10 times by
optimizing the efficient path, which is in good agreement with the analysis.
