As an important transition ecozone, hydro-fluctuation belt is known to be the key area to find the function mechanism between all kinds of ecological factors. We selected the Guanting Reservoir, a large inland reservoir in North China, as the research area. Based on the monthly and annual water level statistic characteristics during 1979-2013 and synchronous Landsat MSS/TM/ETM⁺/OLI image acquired in wet and dry seasons, we first analyzed the spatial and temporal distribution characteristics and its variation trend. Thus based on the water level fluctuation history, using transect sample and overlay analysis, we quantitatively discussed the flooding frequency and duration in hydro-fluctuation belt; moreover, based on the flooding times and years, we explored subzone in hydro-fluctuation belt. It was found that:(1) during1979-2013, the water level in the Guanting Reservoir dropped significantly up to 8.19m. The changing process of hydro-fluctuation belt could be divided into three stages:the intermittent fluctuation period during 1979-1996 with a 4-5-year fluctuation cycle; the shrinking period from 1996 to 2007, whose water level continued to drop to 7.12m; and the frequent fluctuation period during 2007-2013 with a 2-year fluctuation cycle and its inter-annual variability settled to 0.75m.(2)For the last 35years, 118.31km² area of hydro-fluctuation belt was formed because of water level fluctuation. The areas that formed during the three characteristic periods were 80.20km², 76.81 km², and 19.89 km², respectively. The hydro-fluctuation belt that formed in the intermittent fluctuation period was located in the Yongding River Estuary and the flat Kangxi prairie influenced by inflow water and terrain. In the shrinking period, the hydro-fluctuation belt showed an obvious trend of extension to the northwest riparian zone and was formed by water level rising during the frequent fluctuation period. (3)From 1979 to 2013, 25.85% of riparian flooded duration was less than 5 years, and 71.77% of riparian flooded duration was greater than 16 years, which show the obvious characteristics of wetland in the Guanting Reservoir. Furthermore, with the decrease of flooding time, the drought phenomenon of plant was outstanding, and the community coverage and diversity decreased. In the partition of flood frequency, the region with the same flood frequency was distributed discretely in space. Moreover, differences of soil organic matter content in partitions that show higher flooding frequency distribution present a discontinuous status, and regional soil organic matter content shows that precipitation was conducive to soil organic matter.