Abstract: 【Objective】The research was to evaluate the indoor toxicity and field control effect of azadirachtin to Diaphorina citri and provide a scientific basis for the biocontrol of D. citri. 【Method】The indoor toxicity and field control effects of azadirachtin on the 3rd instar nymphs and adults of D. citri were determined by leaf soaking method and spraying method. 【Result】Under indoor condition, the LC50 values of 3rd instar nymphs were 2.77, 1.14 and 0.61 mg/L, respectively after being treated with azadirachtin for 1 d, 3 d and 7 d. However, the mortality rate of adult D. citri was only 13.33% after being treated with 16.0 mg/L azadiracthin for 4d, which had no significant difference with the water control. The field control effects on D. citri nymphs were 14.35%, 49.56% and 86.4%, respectively after sprayed with 800 times diluent of 0.3% azadirachtin EC for 1 d, 3 d and 7 d.【Conclusion】Azadirachtin had good toxicity activity against D. citri nymphs and showed the best field control effect on D. citri nymphs after being treated for seven days, while it had no toxicity activity toadults. Azadirachtin has a favorable application prospect in the control of D. citri nymphs.