Abstract: A field experiment was conducted to study the effects of phosphate fertilizer on utilization of non-structural carbohydrate (NSC) stored in the main root, crown, and stubble of alfalfa (Medicago sativa) during early regrowth after defoliation. NSC is mainly stored in the root and crown. A great deal of starch, the major component of stored NSC, was utilized during early regrowth. With increasing rates of phosphate fertilizer, starch reserves increased in the main root and crown and at 270 kg P₂O₅/ha starch reserves were 73.5% and 31.1% higher respectively than those in the control. Phosphate fertilizer improved the activity of α-amylase and accelerated the hydrolyzis of starch in the main root and crown, thus promoting regrowth by enhancing mobilization of starch reserves for emergence of dormant buds and new shoots after defoliation. The dry weight of plants treated with 270 kg P₂O₅/ha was significantly (P＜0.01) greater than the control 13 days after defoliation. NSC in the main root and crown of alfalfa is the main source of nutrients during early regrowth and phosphate fertilizer improved the storage and conversion efficiency of NSC thus accelerated regrowth of alfalfa after defolition.