Abstract: Sprayed AC reagent 200 mg·L^-1 NaHSO₃,0.5% CO(NH₂)₂,0.2%KH₂PO₄ upon mulberry leaves,it was shown that AC reagent could obviously increase chlorophyll content,raises photosynthetic rate and specific leaf weight,quicken export of photosynthetic products,and enhance the content of soluble sugar and crude protein,etc.Therefore,AC reagent increase the yield of mulberry and improve quality of mulberry leaves.AC reagent raises photosynthetic rate was related to decrease of nitrate reductase activity and appropriate inhibition of photorespiration.