Metro systems are playing an increasingly important role in the cities all around the world, due to the demand of reduction on traffic congestions and energy consumption. The purpose of the present study is to investigate the relationship between the entering traffic and a new conception of centrality Structuality on metro network. The centrality analysis is carried out for study the metro network in Paris. It is found that the coefficient of centrality could help indicate the potential traffic flow. The intersections on metro networks showed a relatively high centrality as well as entering traffic. An “effect of pump” could be observed around the intersections. This method could be applied to compare different network design in the planning phrase, as well as optimize the current metro networks.