<p>With the rapid development of power Internet of Things, malicious code intrusion has become a major hidden danger threatening its safe and stable operation. Although there are some malicious code defense technologies for the Internet of Things or general network environment, the malicious code intrusion solutions specially designed for the characteristics of the Internet of Things in power are still scarce. The existing technology lacks targeted protection for the vertical hierarchical architecture of the power Internet of Things, and fails to fully consider the complex interaction and security requirements differences among the perception layer, the network layer, the platform layer and the application layer. Therefore, this paper uses multiple access control technology to develop a comprehensive vertical border joint defense system against malicious code intrusion in power Internet of Things, and proposes a vertical border joint defense technology based on multiple access control. The technology establishes a joint defense technology system for malicious code invading the vertical boundary of the power Internet of Things. In this technology system, based on the two-way authentication protocol, the user’s initial key is generated after the initial assumption of the two-way authentication protocol, and then the database table structure of the power Internet of Things is established according to this key and the user access key array is generated. On this basis, the user’s identity is authenticated in two ways, such as the legality of the user’s expression and the legality of the card reader. At the same time, after configuring the public key list for the power Internet of Things server and generating the user-key corresponding array, the user’s public key is authenticated according to the security command interpretation protocol, so as to realize the multiple access control of the power Internet of Things. Then, the malicious code intrusion detection method based on cloud model and semi-supervised clustering algorithm is used to detect whether there is malicious code intrusion, and finally the Markov game model is used to realize the joint defense of malicious code intrusion into the vertical boundary of the power Internet of Things. Experiments show that this method can perform multiple access control for different layers of the power Internet of Things, and accurately detect malicious codes of the power Internet of Things. The defense rate can be maintained at a high level of about 97%, and the expected income can reach about 0.97, which can effectively improve the power Internet of Things’ ability to resist malicious code intrusion, reduce security risks, and provide a solid guarantee for the safe and stable operation of the power Internet of Things.</p>