he stress response of Pomacea canaliculata to molluscicide metaldehyde at proteomic level was analyzed in this study,which lays a foundation for future study of the molecular mechanism of resistance to drugs in snail. Proteome of the P. canaliculata liver was studied using the isobaric tags for relative and absolute quantitation (iTRAQ) technology. The results showed that 108 differentially expressed proteins (P＜0.05) with quantitative information were identified,of which 55 were significantly upregulated and 53 were downregulated. The physical and chemical properties analysis and GO (gene ontology) annotation analysis showed that these proteins could be functionally categorized into antioxidant,catalytic and antibacterial functions,affecting the cellular structure composition,muscle contraction,metabolic regulation and immunoregulation and causing neurotoxicity of snail. All the 57 Cytochrome P450 were found to show different expression activity,suggesting that CYP450 may contribute to metaldehyde resistance of P. canaliculata.