Abstract: Discussing the dynamic balance between cultivated land demands and supplies and comprehensively analyzing the driving factors for the changes of the balance, this paper presents the dynamic balance system of cultivated land demands and supplies with the conceptual framework of multi-scales. In accordance with such main processes as monitoring changes, this paper puts forward a forewarning system of dynamic balance between cultivated land demands and supplies at multi-scales, aiming at the driving factors. It also gives some detailed discussion on multi-dimension warning indexes and quantitative analyses on disequilibria in quantity, quality, per capita capacity and time scale.