Abstract: This study aimed to investigate the effect of transient receptor potential melastatin 2 (TRPM2) ion channel on pulmonary microvascular endothelial cell (PMVEC) mitochondrial damage induced by H9N2 influenza virus infection. Basing on the established TRPM2 shRNA PMVEC, in this study, TRPM2 shRNA PMVEC and shRNA PMVEC (control) were infected by the dose of five multiplicity of infection (MOI) H9N2 influenza virus. At 24 and 48 h post-infection, the mitochondria of PMVECs mentioned above was extracted and the protein level was measured by BCA protein assay kit; The SOD activity, GSH level, NOS activity, Na⁺-K⁺-ATPase and mitochondrial complex Ⅳ were measured according to the manufacturer's instructions;The mitochondrial membrane potential change (using mitochondrial membrane potential assay kit with JC-1) and apoptosis (using annexin V-FITC/PI apoptosis detection kit) of PMVEC were observed by laser scanning confocal microscope. The results showed that the activity of SOD, Na⁺-K⁺-ATPase and mitochondria complex Ⅳ and the level of GSH in TRPM2-shRNA PMVEC were significantly higher than those of shRNA PMVEC (control) after H9N2 influenza virus infection (P<0.05 or P<0.01); However, the NOS activity was dramatically lowered than that of control PMVEC (P<0.01). Moreover, the observation of electron microscope showed that the damage of organelles of TRPM2-shRNA PMVEC was not as serious as that of control shRNA PMVEC; Furthermore, the mitochondrial membrane potential level also was higher than that of control shRNA PMVEC. The apoptosis of TRPM2 shRNA PMVEC detected by annexin V-FITC/PI staining showed that there were less PMVECs stained by green fluorescence in cytomembrane and red fluorescence in nucleus than that of control shRNA PMVEC. The results demonstrated that gene silencing of TRPM2 by shRNA alleviated effectively SOD, GSH, Na⁺-K⁺-ATPase, mitochondrial complex Ⅳ in PMVEC infected by H9N2 virus, and further to prevent the mitochondrial damage and apoptosis of PMVEC.