Using flue-cured tobacco cutters as experimental materials,changes of color indexes (L*,a*,b*),states of tobacco leaves and their relationship with main chemical components were studied to provide a theoretical basis for the optimization of curing technology and precise and intelligent control of curing process.Results showed that color indexes of front and back side of tobacco leaves had the same trends during bulk curing.It had big changes in the prior period,and small changes during later periods of curing process.Front side changed faster than back side.Thickness shrinkage showed a large change rate since the start of the curing,while it slowed down in stem-drying stage.The rest of the state indexes had larger changes in middle and smaller changes in prior and later period.Correlation analysis showed that certain relationships existed among color indexes,states of tobacco leaves and chemical components,most of which were significant or extremely significant.Regression analysis indicated that the regression equation had a high fitting degree and these models could be used to predict the states of tobacco leaves and chemical components.