Abstract: The appearance and chemical variation relationship of burley tobacco leaves in air-curing process was studied.The results indicated that the quantity of dry matter, tatal sugar and total nitrogen more decreased in wilting and yellowing period, that the browning and wilting periods were the important stage of water loss and that browning was the appearance characteristics of leaf cells breaking, dissolving and disappearing and the largest range that leaves turned thin was in browning period. Keywords Burley tobacco Air-curing Variation.