The Oriental vole (Microtus fortis) is an agricultural pest in Dongting Lake area,and causes serious damage to crops when the beaches are flooded (June to October) .Based on the habits of migration of the vole between the two habitats (beaches and cropland) ,building "rodent-proof wall" along the dike surrounding the beaches is the best way to prevent voles from moving into the adjacent cropland.In order to confirm the effect of the "rodent-proof wall",investigation using snap traps was conducted in 2012 in April (in beaches before migration) and July (in farmland after migration) .Trap success in farmland with a "rodent-proof wall" on the dike was 0.52%,and was significantly lower (x2 = 3.9,P = 0.048) than that in farmland without "rodent-proof wall" (1.76%) after the voles had immigrated into farmland from the adjacent beaches.Compared to the population density in beaches,a decrease (98.5%) of population density in farmland with a "rodent-proof wall" was significantly (x2 = 11.1,P = 0.01) higher than that (86.6%) in farmland without a "rodent-proof wall",in spite of rodent control conducted by farmers in the unprotected polder.These results suggested promotion of a "rodent-proof wall" along the dikes in Dongting Lake could limit crop damage.