Abstract: The authors studied changes of leaf area index (LAI), dry mater of aerial part and dry mater of hypogeal part, clarified impact of different transplanting periods, and determined the best transplanting date of sugarbeet after change of the sink-source relationship. The different transplanting periods were adopted by taking‘KWS6167’as the test material in the same nursery of seedlings, a total of four transplanting treatments were set, A: April 26, B: May 1, C: May 6 and D: May 11. The results showed that: the LAI was different in different treatments, and the duration of identical LAI was different in different treatments; the dry matter weight of aerial part in respective treatment was inconsistent, A, B and C treatment showed a single peak change trend, D treatment had an increase trend, there was a positive correlation between dry matter weight of aerial and leaf area index in all treatments; with the increase of LAI, the dry matter weight of hypogeal also increased so that they showed a significantly positive correlation from June 10 to August 10; with the decrease of LAI, the dry matter weight of hypogeal increased from August 10 to October 7, the dry matter weight of hypogeal and LAI showed a significantly negative correlation.