Abstract: The botanical pesticide azadirachtin was microencapsulated using interfacial polymerization. The technical conditions for azadirachtin microencapsulation were optimized by orthogonal experiment. Results show that the encapsulating yield of azadirachtin reaches(83.16±1.22)% under the following conditions: the ratio of toluene-2,4-diisocyanate(TDI) to hexamethylenetetramine was 3︰4(m∶m) as the wall materials, the proportion of azadirachtin dry powder to wall materials was 30︰7(m∶m), the ratio of ethyl acetate??to xylene was 3︰2(m∶m) as solvent, respectively. Pot culture experiment shows that the microencapsulated azadirachtin has good insecticidal effects with bioactivity and a long effective duration.