Abstract: With the development of advanced digital, communication, and Internet technologies, the traditional power system has been transformed into a new power system with digitalization, automation, and efficient management. However, the deep integration of cyber and physical domains makes the network, hierarchy, and components in the new power system more complex, and the frequent access and information interaction of a large number of intelligent electronic devices makes malicious attacks easier, such as data theft and tampering, blocking of communication channels, and damaging key equipment, which poses a great threat to the security, stability and economy of the new power system. This has triggered great concern in the academic community. First, this paper analyzes the structure of the new power system and the potential threats faced by the new power system, and conducts an in-depth analysis of the attack modes to the new power system from the three levels of the control layer, network layer, and physical layer. Then, it summarizes in detail the three-layer security defense methods before, during, and after the attack on the new power system. Finally, the future technological development prospect of the new power system security research is clearly elaborated to provide technical support for the construction of the reliable, secure, and robust new power system.