Abstract: In order to improve the usability of tobacco leaves with quality defects,the effects of casing immersion-elution conditions on the leaves were studied.The results showed that:1) Casing immersion-elution improved the sensory quality of tobacco leaves,the cell structure in the leaves became opener and the chemical composition more harmonious.2) With cost effective Casing F(propylene glycol),the appropriate immersion-elution conditions were concentration 1.5%-2.5%,at temperature 65℃,for 10-15 sec.3) The results of production application indicated that comparing with untreated leaves,the processed leaves offered consistent sensory style,slightly better quality,and less carbon monoxide and tar yields.Casing immersion-elution could promote the utilization value of leaves with quality defects.