In this experiment,the flue-cured tobacco variety namely ‘K326’ was taken as experimental material.The glutamine synthetase inhibitor (glufosinate-ammonium) of 0.005% and 0.01% (mass fraction) was sprayed over the leaves in the 7th day to technical maturing stage,respectively.The curing characteristics were studied in the process of roasting tobacco.The results revealed that the contents of chlorophyll,carotenoid and activity of polyphenol oxidase reduced;the water loss rate and MDA content of leaves increased;the proportion of yellow leaves increased and variegated tobacco decreased.This study showed that flue-cured tobacco leaves were more easily turning yellow,the easy curing potential and leaf coloring characteristics were improved,reduced the browning reaction’s happening.However,high concentration of glutamine synthetase inhibitor accelerated the rate of leaf water loss which is bad for fixing color.The percentage of green tobacco increased and the appearance quality of flue-cured tobacco leaf reduced.