The booming of Internet has brought new challenges to software engineering. In the network age, software industry has undergone a transition from manufacturing industry to the service trade, software doesnpsilat have clear hierarchy structure, specific life cycle and definite system border any longer. On the contrary, both software itself and the environment it works in are all networked. In this paper, we explore an idea of software engineering from the perspective of complex networks. First, we present a skeletal description to abstract software structure into network topology. Evidence shows that software systems have the characteristics of small world, scale-free and high clustering. Then we point out three aspects of the influence to software engineering based on the characteristics of complex network. Finally, the most promising development trend of software engineering in the future is predicted.