Flood- generated gravity flow (hyperpycnal flow) is the research focus of gravity flow sedimentology in recent years. In the past, the sedimentary dynamic interpretation of hyperpycnal flow was mainly based on the fluid properties supported by turbulence. The possible transformation of its fluid properties and identification of related sedimentary records is still a question for us. Recent studies have revealed that a variety of transitional flows can be formed during the deposition process of gravity flow, with special flow transformation mechanisms and deposition characteristics. Methods:Through the investigation of the literature review, the research progress on the basic characteristics and depositional mechanism of transitional flows is introduced. And, its geological significance for the study of flood- generated gravity flow is also discussedResults: The results show that: under the influence of a small amount of clay, the nature of sediment gravity flow can be transformed from turbulent flow to laminar flow. The transformation of transitional flow mainly depends on the interaction between the clay mineral content related fluid cohesion and the turbulent force controlled by the velocity. During this process, a variety of transitional flows could be formed. Unique bedform types such as large current ripple, low amplitude bed wave with sandy laminae and clay laminae could be generated. Although the experimental study reveals the possible bedform characteristics of transitional flows, the interpretation of transitional flows in the subsurface ancient hyperpycnal flow sedimentary records is still lacking. The transformation mechanism of transitional flows and their sedimentary response in hyperpycnites need to be further explored. The latest research reveals that the special sedimentary bedform related to the transitional flows can be identified in the sedimentary records. The transitional flow deposition could give implications for the sedimentary mechanism of flood - generated gravity flows. Conclusions: Transitional flow sedimentology could provide a new perspective for further understanding the fluid transformation and sedimentary response in the process of gravity flow deposition. And, transitional flow may have a broader range of significance in sedimentary geology research.