Abstract: OBJECTIVE To study the effect of tea polyphenols(TP) on apoptosis of rat alveolar macrophages (NR8383) induced by SRM 2786 (PM_2.5 standard) and to explore the underlying mechanism. METHODS The NR8383 cells were cultured in vitro and divided into 6 groups, including control group, model group(125 μg·mL^-1 SRM 2786 exposure group), diverse concentrations of TP groups(43.75, 87.5, 175, 350 μmol·L^-1TP+125 μg·mL^-1 SRM 2786). The following parameters were evaluated after 24 h intervention:cell survival rates, generation of reactive oxygen species(ROS) and NO, production of inflammatory cytokine release(IL-6, IL-1β and TNF-α), apoptosis rate, mitochondrial membrane potential, activities of caspase-3/caspase-9. RESULTS Compared to the control group, SRM 2786 could significantly inhibit the NR8383 cell survival rate, promote the release of NO and ROS, promote the release of three inflammatory factors, mitochondrial damage, apoptosis and increase the activity of caspase-3/caspase-9. In contrast, TP effectively inhibited SRM 2786 induced NR8383 cells oxidative damage, inflammation, mitochondrial damage, and finally elevated cell survival rate via inhibiting caspase-3/caspase-9 activities. CONCLUSION TP can inhibit the mitochondrial apoptosis of NR8383 cells induced by PM_2.5 and improve the activity of NR8383 cells by reducing cell oxidative damage, inflammatory damage and caspase-3/caspase-9 activity.