Libero players play a very important role in volleyball teams. They are responsible for the serving and defending, the keys for receiving-attack and defense-attack systems. Libero players have the special permissions for substitution, allowing the maximization of their effectiveness in the back row. On the other hand, if the teams fail to use libero players at the right time, their effectiveness would suffer. Hence, how to maximize the effect of libero players is one of the most important tasks for volleyball coaches. This article investigates the strategy of using the libero players. The strategy is the key for winning in volleyball.