【Objective】On the basis of initial studies， the dosage of PP333 were screened and optimized for Narcissus to study the mechanism of dwarfing regulation in Narcissus. 【Method】Narcissus tazetta L. var. chinensis Roem sampled from Zhangzhou was treated with 40 mg/L PP333 to investigate the nitrogen and carbon metabolism in leaf. 【Result】The PP333 treatment decreased the inorganic nitrogen （ammonium and nitrate nitrogen）， increased the ratio of NO3-N to NH4-N in leaf， as well the total nitrogen content before bolting stage. The total soluble sugar and reducing sugar in leaf， and percentage of reducing sugar in total sugar also increased. The sucrose content in leaves of PP333 treated plants did not show regular changes compared to the control. 【Conclusion】Treatment of 40 mg/L PP333 changed the carbon and nitrogen metabolism of dwarf Narcissus significantly. The nitrogen content and changes in its form were closely related to Narcissus dwarfing， and the total sugar and reducing sugar content were found more closely related to Narcissus dwarfing than sucrose content.