The effects of magnesium fertilizer on flue-cured tobacco growth and development, yield and quality in south Anhui was studied by methods of field experiment and lab analysis. The results showed that: rational application of Mg could promote the growth and development of tobacco effectively, and improve yield, balance the chemical components of tobacco leaves and as a result the quality of tobacco leaves were improved. Under the condition of this experiment the optimal Mg application was 300 kg/hm2 MgSO4·7H2O, and the agronomic characters, all of dry matter accumulation, yield, and tobacco leaf quality were the best.