Artificial Intelligence (AI) technology greatly enhances human abilities by improving perception, comprehension, action, and learning. Additionally, Brain-Computer Interface (BCI) technology offers distinct benefits for human-computer interaction in various applications. Human-machine shared control technology based on brain-computer interface combines the features of human and machine intelligence, and offers numerous benefits when compared to direct brain-computer interface control technology. This paper elaborates on the fundamental structure of the brain-computer interface control system, and provides a detailed explanation of the three-tiered frameworks of the human-machine shared control system. By leveraging the unique strengths of humans and machines, the design of six internal sharing strategies is explored.In addition, an outlook on future research directions and development trends is made, aiming to provide new ideas and directions for the research of human-machine shared control technology.