Abstract: The Ningbo-Shaoxing Plain, a well-known area of water network in China, has been in the historical periods a lake group consisting of 217 major lakes, a lake group which played an important role in the development of the human society of the region, and which was decidedly influenced in its vicissitudes by the enhanced activities of man. Owing to the special regional physical and socio-historical conditions, there has existed from the beginning a relation of mutual dependence and contradiction among man and the land and water in the region, and the lake group, evolving without intermittence in such contradiction and conflict, has experienced a process of fluctuation from hilly areas to the plain and vice versa. The lacustrine fluctuation essentially a migration of water bodies, reflects man's readjustment of the physical environment, with a purpose of utilizing, under the situation of the high-speed growth of the population, the land resources of the region to the maximum. The fluctuation in which both borizontal and vertical movements took place, has resulted in the change of the property of the lakes and their morphological improvement, which were realized, along with the migration of water bodies, mainly in vertical movement.In consequence of the vices of feudalism existing long since, and of the mistakes in agricutural policy in certain respects after liberation, the proper exploitation of the water resources of Ningbo-Shaoxing Plain has not been fully resolved, and the lacustrine fluctuation of the region is still to be treated in further researches.