Abstract: Through analyzing the literature on the size of rare earths reserves in qualitative research, uti -lizing the relationship between real supply and predicted supply deal, and using simulation model of re -serve deal, quantitative calculation of the storage reserves of rare earths is conducted. Based on the data of rare earths production, sales and storage from 2000 to 2011, three plans are made. The volatility index of supply deal in each plan is 0 %, 5 %, 10 % respectively. Preliminary estimation of the reasonable re -serve deal of rare earths in 2012 is obtained when analog computation is used for the annual maximum reserves, minimum storage and reasonable reserve deal in each plan. In accordance with the national fi -nance, economic situation at home and abroad, the development of rare earth industry, reserves on high, medium or low levels will be chosen when decision -making on national reserves is needed. Under the guidance of different levels of reserves, the corresponding size of reserves will be adjusted.