据养分平衡原理对落叶前后刺槐不同器官养分的迁移动态进行了分析，计算了各养分元素参与内循环和外循环的养分通量及循环率，结果表明：刺槐叶子在凋落前，氮、磷、钾、镁、硫均发生不同程度的回流，回流率分别为６３．９４％、６１．８３％、７６．３９％、１８．３３％和６９．６０％。钙却发生顺流，使落叶、果的钙含量增加１倍之多。在各养分元素中，钾的总循环率最高达５９８１％，其它较低，约为２６１７％～３７．１９％，而且氮、磷、钾以内循环为主，内循环率分别为２２８６％、１６８１％和５１５％，而外循环率大致为８３５％～９９９％。钙、镁、硫的内外循环率基本接近，大致为１５１０％～２１８３％。且有迹象表明，在落叶前后刺槐仍然从土壤中摄取少量的钾、镁，而随雨水淋溶或分泌向外排出少量的硫。 According to the principle of nutrient balance, the nutrient mobilization of different organs of Robinia pseudoacacia before and after deciduous leaf was analyzed. The nutrient fluxes and the circulation rates of various nutrient elements involved in internal and external circulation were calculated. The results showed that: Potassium, magnesium and sulfur all had different degrees of reflux, and the reflux rates were 63.94%, 61.83%, 76.39%, 18.33% and 69.60% respectively. Calcium occurs downstream, so deciduous, calcium content increased by as much as 1 times. In the nutrient elements, the total potassium cycle rate of up to 59  81%, the other lower, about 26  17% ~ 37.19%, and nitrogen, phosphorus and potassium within the loop, the internal recycle rates were 2286%, 1681% and 515%, while the external circulation rate was about 835% ~ 999%. The internal and external recycle rates of calcium, magnesium and sulfur were almost the same, about 1510% ~ 2183%. And there are indications that Robinia pseudoacacia before and after the leaves still ingest a small amount of potassium and magnesium from the soil and excreted a small amount of sulfur as the rain leached or secreted.