Abstract: In order to optimize upper leaves during tobacco curing, two treatments (optimized curing and conventional curing) were set up. By analyzing leaf samples collected during curing, the coordinated variations of moisture content, color and chemical components of the leaves under different curing conditions and the quality differences of cured leaves were studied. The results showed that: 1) The dehydration of upper leaves was relatively difficult at the early stage of curing, and it occurred mainly from late yellowing stage to color fixing stage. 2) The dehydration of tobacco leaves during curing closely correlated to the variations of color and chemical components. In the process that the moisture content decreased from about 75% (fresh tobacco leaves) to about 60%, the color of leaves changed from yellow-green to light yellow accompanied by large amounts of starch degradation. In the process that the moisture content decreased from about 60% to about 10% (basically dry leaves), the color of leaves changed from yellow to dark orange and free amino acid contents decreased significantly. 3) During curing, the moisture content in tobacco leaves extremely significantly positively correlated with L (lightness)and b (yellowness)values, while extremely significantly negatively correlated with a (redness)value. The content of reducing sugar had significant positive correlations with L, b and a values. 4) For the top six upper leaves from central Henan tobacco-producing areas, no dehydration of leaves occurred at yellowing stage, and fast dehydration due to sharply reduce of wet bulb temperature at early color fixing stage should be avoided. The regulation of processing parameters at the middle and later stages of curing should aim to promote the reasonable conversion of chemical components in tobacco leaves.