Abstract: The institution of linking the increase in land used for urban construction with the decrease in land used for rural construction (LIDL) was a creative design and arrangement which was originated from the thought of cultivated land requisition and compensation balance, setting the farmland preservation as its aim and core. During the national pilot study over these years, the institution exposes many problems and faces the query from various circles of society: should it be paused, carried on or promoted? Basing on this background, this article analyzed the evolution of the strategy deeply and explores the theoretical and realistic basis of its forming. Meanwhile, we mainly study the root and crux of this policy and put forward the proper attitude and view in researching it and the key points and difficulties of its further study, basing on comprehensive review of the attitudes and views on the institution from the governments and academic circles after making the data collected and finished. Only did we know the essence of these problems so clearly that we could have this creative institution taking effect.