Abstract: The control effect of azadirachtin with trunk injection at 1-3 mg per cm DBH(diameter at breast height) was above 90% on Panonychus citri(McGregor) 7 days after injection in the field,and remained above 75% in 60 days.The sublethal doses of azadirachtin on different developmental stages of P.citri were determined and their long-term effects on P.citri population were discovered to be the extension of developmental duration and reduced fecundity.