In this paper we introduce a novel method, LCDA, to identify the communities in large complex network based on ??local community??. Time complexity of our algorithm is O(n<k>3 Ln(n) where <k> is the mean degree and n is the number of vertices in the network. It is very useful in analyzing very larger complex network. By applying LCDA on Zachary club network we get better structure than classical NG algorithm and higher speed than SA method. Our algorithm exhibits good accurateness by testing much larger complex networks further.