【Objective】To investigate the effect and mechanism of azadirachtin on proliferation and apoptosis in Plutella xyllostella embryonic cells. 【Method】P. xyllostella embryonic cells were divided into azadirachtin treated and untreated groups, the inhibition rate of cells proliferation was detected using CCK-8 kit. The cell death and apoptotic body were observed using laser confocal microscope after stained by PI and DAPI respectively. The expression of Caspase-3 and the phosphorylation of pathway protein Akt were detected using Western-blotting.【Result】Azadirachtin had significant inhibitory effect on the proliferation of P. xyllostella embryonic cells, and the effect was dose-dependent. IC₅₀was 4.4 μg·mL^-1 in 24 h. Dead cells could be observed in azadirachtin treated group after stained by PI, and apoptotic body could be found in the same group after stained by DAPI. Caspase-3 protein was cleaved and Akt phosphorylation was inhibited.【Conclusion】 Azadirachtin has significant inhibitory effect on the proliferation of P. xyllostella embryonic cells. By inhibiting the activation of Akt signaling pathway, azadirachtin can induce cells to produce Caspase-3-dependent type I apoptosis.