With the method of long-term experiment and statistical analysis,time variation of leaf traits and their correlations in a whole growth season were studied.The result showed that:（1） leaf area increased with growth time prolonging and the curve took on S pattern.Its relationship could be described with y=e（5.528 93-5.104/x）.The specific leaf weight increased with growth time prolonging and its model was cubic y=0.000 002 x30.000 8 x2+0.088 1 x+2.942 1.Leaf water content in the growth season increased in the model y=-0.000 1 x3+0.031 9 x2-3.616 3 x+424.56.Season dynamics of leaf fresh weight in the growth season was S pattern and its model was y=e（1.770 8﹣36.299/x）.Leaf dry weight was y=0.042 5 x0.697 1.Dry / fresh ratio was y = 0.000 000 009x3-0.002 6 x2+0.262 x+16.946.（2） a significant positive correlation existed between leaf dry weight and leaf area.Their relationship could be described with y=0.008 1 x﹣0.253 6.Relation of leaf fresh weight and leaf area was significant positive correlation and its model was y=0.020 7 x1.020 3.Leaf dry weight and leaf water content was significant negative correlation and its model was y=7.710 6e﹣0.002 7 x.With the method of municipal statistical analysis,it confirmed that the relation among the leaf dry weight,leaf area,leaf water content,specific leaf weight,dry / fresh ratio was y（leaf dry weight）=0.006 6 x1（leaf area）+0.003 22 x2（leaf water content）+0.187 95 x3（specific leaf weight）+0.035 27 x4（dry/fresh ratio）-3.071 2.（3） it proved that season variation of paulownia leaf modal traits closely related to the local climate.The other traits and their mechanisms needed further study.
