The invention disclosed an improved k-shell decomposition method to identify influential nodes in an online social network. The decomposition method involves providing a number to indicate propagation strength of each node and providing a number to indicate engagement strength of each node. The propagation strength and engagement strength is added to form a weight for each node. The weight is used to indicate weighted degree of each node. Each weighted degree is assigned a particular shell based on the weight. Nodes in higher shell order indicate nodes having higher influence of nodes in the network.