Urban water system planning is the special planning of urban master planning, and focuses on ensuring flood control and ecological security. Therefore, it is based on water conservancy disciplines, ignoring its coupling with urban planning and territorial spatial planning to some extent. The composition, structure, distribution pattern, scale and other factors of urban water system affect its security, ecological and landscape functions, and its spatial layout is extremely important. Paper analyses the layout of water system, chooses the landscape accessibility of water system space as the research object, establishes the model and analysis framework, takes the different scale cities as the research scope, chooses three water system planning of Xixian New Area as the case, concretely analyses and demonstrates the spatial accessibility of water system planning, and holds that water system and urban safety should be guaranteed at the macro level, and scientific water system planning should be hold at the medium level, and landscape design is in micro-level. The accessibility of water system landscape is an important aspect of water system planning, which provides scientific basis for rational layout and planning design, creating a good urban space environment.