With the statistic data from 1949-2006,the change rate year by year for quantity of cultivated land,GDP,population and grain output was obtained,which were decomposed in multi-scale by selecting morlet wavelet.The result showed that each element had wave period of multi-scale,scale of 15 years was the main cycle of the fluctuation for cultivated land quantity,population and grain output,scale of 5-10 years was the main cycle of GDP fluctuation;The fluctuation of cultivated land quantity had negative correla...