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A labyrinth seal consists of several annular sealing teeth arranged in sequence around the rotating shaft; gaps and expansion chambers are formed between these teeth. As the fluid to be sealed passes through these intricate labyrinthine gaps, a throttling effect occurs, thereby preventing leakage. Labyrinth sealing is the most basic type of sealing for inter-stage and shaft-end connections in centrifugal compressors. Depending on their structural characteristics, it can be divided into four types: smooth type, serpentine type, stepped type, and honeycomb type. 1. Smooth labyrinth seal: The smooth labyrinth seal comes in two configurations – integral and patch-type. It has a simple structure that makes it easy to manufacture, but its sealing performance is poor. 2. Twisted labyrinth seal: The twisted labyrinth seal also comes in two configurations – integral and insert-type. Its structural feature is that the protrusion heights of the sealing teeth vary, with high and low teeth arranged alternately. The shaft surface corresponding to it features specially designed ridged and grooved patterns. This combination of high and low teeth along with these ridged and grooved patterns transforms the otherwise smooth sealing gap into a twisted one, thereby increasing flow resistance and enhancing the sealing efficiency. However, it can only be used in cylinder blocks or partitions with horizontal split surfaces, and the sealing element must also be of the horizontal split type. 3. Stepped labyrinth seal: Structurally, the stepped labyrinth seal is similar to the smooth labyrinth seal, yet its sealing performance is comparable to that of the twisted labyrinth seal; it is commonly used on impeller covers and balance discs. 4. Honeycomb labyrinth seal: The sealing elements of a honeycomb labyrinth seal are welded together in a honeycomb pattern to create expansion chambers with complex shapes. Its sealing performance is superior to that of conventional sealing types, and it is suitable for applications with large pressure differences, such as the sealing of balance discs in centrifugal compressors. The manufacturing process of honeycomb labyrinth seals is complex; these seals have high strength and provide good sealing performance.