Abstract: As a result of rapid development of social economy in some areas in last few decades, lake ecology has been destroyed by the industrial waste water and domestic waste water around the lake catchment, and the lake water environment pollution and lake eutrophication is very serious. The studies based on the relationship between wet pollen and lake nutrient state in sediments from a core of central Longgan Lake located in the boundary between Hubei and Anhui province show that the degeneration of wetland vegetation caused the land nutrient discharges by human activities around the lake catchment and the lake nutrient enriched relatively. Human activities have destroyed the wetland in the area of Longgan Lake, weaken the ecology function of wetland, and accelerated the deterioration of lake ecology.