In the digital age, computer networks carry key functions such as information transmission, business transactions, and social interaction. However, with the increasing frequency of network attacks and the increasing number of data breaches, the security of computer networks has become particularly prominent. This paper explores how to optimize the architecture design and strengthen security measures, such as deploying advanced firewalls, intrusion detection systems, and implementing access control, to cope with complex and changeable network threats, improve the security of the network environment, and provide support for the sustainable development of enterprises.