Online social networks have become ubiquitous in our daily life, which create the phenomenon of the Big Data. Figuring out the information diffusion over online social networks has become a hot topic. However, most of the existing works focus their attention on the spreading dynamics of users' information rather than on the essence of the network topology. In this paper, we propose a value strength based forwarding nodes' selection scheme from a perspective of the network science, which is beneficial in terms of improving the information coverage ratio. Furthermore, sufficient experiments are conducted both over a range of complex network topologies and over a real-world online social network, Flickr. Indeed, the concept of the value strength plays an important role in selecting critical forwarding links and nodes.