With the rapid development of smart grid technology, the security of Industrial Control Systems (ICS) has become increasingly important. The IEC 61850 protocol, as a key standard in the smart grid, aims to improve automation and interoperability in power systems. However, with its widespread application, IEC 61850 has also exposed various security vulnerabilities, making it a target for potential attackers. This content will explore the application of IEC 61850 in smart grids and the security threats it faces, including known vulnerabilities, attack vectors, and real-world case analyses. Special attention will be given to how these vulnerabilities can be exploited for attacks, and the impact of such attacks on the operation of power systems. Through case studies, the goal is to provide a deeper understanding and to encourage the relevant industries to pay more attention to ICS security, in order to develop effective protective measures and ensure the secure operation of the smart grid.