From the view of complex networks and emergent computation, a new emergence model of public opinion is built. It is based on small-world model, and takes Internet users as agents. Then the system parameters and realistic interactions in this model are set. Simulation results show that our model can demonstrate the whole evolution process of formed or unformed public opinion. The formation evolution of public opinion is in accordance with the real network of public opinion. We can get all kinds of public opinion forms via setting different model parameters. By comparing with the existing network model, there is an obvious advantage for the interaction rules and forms in our model, and it is realistic and reasonable. As a new model for the complex system, it can be used as one of the objects for studying the network behaviors and emergent computation.