Ecosystem services are recognized as being able to be spatially transmitted within geography in diversified flow forms, subsequently exerting their service utility in different locations. Complexity makes the concept of ecosystem service flow a frontier issue in the field of ecology and geography. However, the theoretical cognition of ecosystem service flows is still in its infancy. Most of the existing studies have been conducted using the basic framework of "service supply-service flow-service demand" proposed by SPAN conceptual model. Although abundant academic research has been made on the static cross-section changes of ecosystem services in geography, the current dynamic cognition of the whole life cycle process of human ecological well-being is still insufficient. Considering that the conduction of ecosystem service flow can be regarded as a kind of spatial motion process, which has the characteristics of motion relativity, energy conservation and structural continuity like general fluid. This study introduced the basic theory of hydrodynamics into the classical framework, and try to establish a research framework of the three-stage "formation-driving-displacement" movement of ecosystem service flow. Through this new framework, we explained the formation, driving and displacement mechanisms of ecosystem service flows using the modular decomposition method. The study shows that: (1) the formation of service flows originates from the support of material and environmental bases in the open system, which is manifested as the gradient potential difference in the heterogeneous spatial pattern due to the mismatch of ecosystem service supply and demand. (2) The essence of service flow drive is the change of force and energy in the process of movement, which can be broadly subdivided into three types of drive (geophysical-chemical natural processes, biome behaviour as well as human socio-economic activities) and five driving factors (natural, biological, market, policy and perceptual). (3) The spatial displacement of ecosystem service flows can be abstracted as a function of mass points in three-dimensional coordinates, which can be portrayed comprehensively through coverage and flow paths, and is affected by a combination of factors such as fluid content, environmental media, and transit carriers, and is a dynamic presentation of the ecosystem service patterns-processes-scales within the human-land coupling system. This study aimed to elucidate the common rule and spatial characteristic behind the diversified ecosystem service flow phenomenon within the human-earth coupling system, which can not only help to enrich and expand the theoretical system of ecosystem services, but also provide support for guiding the direction of high-quality and sustainable development.