Landscape spatial pattern is an important focus of research in landscape ecology. Much attention has been paid to research on patch and corridor structure for certain land use types at the local or regional scale as opposed to the spatial gradient for one natural land cover type at the watershed scale. In particular spatial gradients for wetland landscape at the watershed scale have not yet been studied. Wetlands are unique among watershed environments because they are terrestrial habitats with strong effects on and strongly affected by aquatic environments. This paper primarily addresses the particular spatial gradients of the wetland landscape within a whole watershed, based on the common spatial principles of landscape ecology and some recent practical research. Results show that the landscape pattern of wetland types within a watershed is controlled by the gradient in topography and hydrological regime. It exhibits gradient features in three aspects: the longitudinal gradient from the headwaters to the mouth of rivers, the transverse gradient considered as a cross section of the floodplain, and the internal structure as species assimilation or heterization within a patch, or the ecosystem composition in patches of landscape. The complexity and continuity of the wetland landscape in the longitudinal gradient, the transverse gradient and the internal structure within the watershed play a significant role in reducing downstream flooding, preventing erosion, maintaining channel stability and water quality, as well as providing corridors for species movement and habitats for some endangered and threatened species. However, both natural factors and human activities can affect the overall pattern of wetland gradient in a watershed. The rate of changes are determined largely by more recent human impacts such as land reclamation, river channelization, and dam construction, which have significant impacts on the longitudinal and transverse gradients and the internal structure of wetlands landscape within a watershed whereas natural factors such as dynamic channel changes and flooding only affect the internal structure of the wetland landscape.