Centroid of a graph is a structure composed of nodes closest from all others. This suggests the idea of center of mass average of all edges, weighted by the local density or specific weight. Computing this centroid in a classic way needs a global view of the graph environment. In this paper, an algorithm using ant colony is proposed to compute an approximate solution of the cen- troid using a local view of the graph. This allows to study the centroids of complex networks such as protein-protein interaction networks and also thus generated by social interactions or Internet, for example.