Carbocisteine is a mucolytic drug with anti-oxidative effect, we had previously proved that carbocisteine remarkably reduced the rate of acute exacerbations and improved the quality of life in patients with chronic obstructive pulmonary disease (COPD), however, very little is known about its mechanisms. In this study, we aimed to investigate the anti-inflammatory effects of carbocisteine against hydrogen peroxide (H2O2). A549 cells were cultured in vitro and treated with H2O2 as damaged cell models, carbocisteine was administered 24h prior to or after H2O2 exposure, and the protective effects of carbocisteine were determined by MTT, qRT-PCR, ELISA, western blot and immunofluorescence assays. The results showed that carbocisteine could increase cell viability and decrease LDH, IL-6 and IL-8 levels in the supernatant. Additionally, carbocisteine decreased IL-6, IL-8, TNF-α, IP-10 and MIP-1β mRNA in a dose-dependent manner. Moreover, carbocisteine could attenuate phosphorylation of NF-κB p65 and ERK1/2 and inhibit the nuclear translocation of pNF-κB p65 induced by H2O2. In conclusion, carbocisteine inhibited H2O2-induced inflammatory injury in A549 cells, NF-κB and ERK1/2 MAPK were the target pathways.