Abstract: The effects of molybdenum application on the AsA content and PPO activity in tobacco leaf during early curing stage and the grade of cured leaf were investigated with field experiments,tobacco of cv.K326,Yunyan85,CB-1 and Honghuadajinyuan(Hongda),was sprayed with molybdenum fertilizer on leaf surfaces.The results showed that for soil deficient of Mo(0.03 mg/kg available molybdenum),the AsA contents in ripe leaves of K326 and Yunyan 85 increased significantly by foliar spray of molybdenum,and the AsA content in tobacco leaves of the 4 cultivars was generally higher than that in CK at early curing stage(0 to 72 h).Foliar spray of molybdenum evidently reduced PPO activity in leaves of K326,Hongda and CB-1,PPO activity in leaves of the 4 cultivars was basically lower than that of CK at early curing stage,especially in 0 to 48 h.Molybdenum application significantly increased the percentage of high and middle grade leaves and decreased the percentage of variegated leaves.