Abstract: The correlation of film-cover and roots and yield, and quality of flue-cured tobacco was studied by field experiment. The results indicated that the length, quantity and dry weight of roots covered film at different staged was higher than those without film-cover. The length, quantity and dry weight of sample roots at 80d after transplanting was obviously positive correlative with film-cover time. The leaf yield and output value was positive correlating with the 80d-aged or 100d-aged roots length. The root quantity at 60d was obvious negative correlative with the content of reducing sugar of bottom leaf but was obvious positive correlative with the K content. The 80d-aged or 100d-aged root length was positive correlative with reducing sugar content of upper leaf, the 100d-aged root dry weight was positive correlative with the K content of upper leaf. The smoking quality of mulching treatment was higher than that of no mulching. Mulching film can improve the quality of tobacco leaf.