Objective: To investigate the effect of pyrrolidine dithiocarbamate (PDTC) on acute lung injury secondary to acute necrotizing pancreatitis (ANP) in rats. Methods: Thirty-six adult SD rats were equally randomized into the sham operation group, ANP group and ANP+PDTC pretreatment group. ANP model was induced by retrograde injection of 5% sodium taurocholate into biliopancreatic duct, and the animals of the PDTC pretreatment group were intraperitoneally injected with PDTC (30 mg/kg) l hour prior to ANP induction. All the animals were sacrificed 6 hours after model establishment, the alveolar macrophages (AMs) were harvested via bronchoalveolar lavage (BAL), and then the apoptosis of AMs was detected by flow cytometer and the activation levels of NF-κB and CYLD in AMs was determined by immunohistochemistry and Western blot method. The contents of TNF-α and IL-1β in the bronchoalveolar lavage fluid (BALF) were also detected. Meanwhile, the myeloperoxidase (MPO) levels of the lung tissues were measured, and pathological assessment of the lung tissues was performed. Results: No pathological change was noted in lung tissues of the sham operation group, while the lung tissues of both the ANP and PDTC pretreatment group showed marked pathological changes such as congestion, edema and accumulation of inflammatory exudates, but these changes of the PDTC pretreatment group were relatively mild compared with those of the ANP group. The MPO activity in the lung tissues, and the contents of TNF-α and IL-1β in the BALF were all significantly increased in the ANP group compared with the sham operation group (all P<0.05), while the elevations of the above parameters were markedly inhibited in the PDTC group and their differences with the ANP group had statistical significance (all P<0.05). The apoptosis rates of AMs of the sham operation group, ANP group and PDTC group were (3.47±1.45)%, (1.16±0.31)% and (1.80±0.60)% respectively, and the differences among the groups had statistical significance (all P<0.05). The immunohistochemical staining indicated that the NF-κB in the AMs of the sham operation group, ANP group and PDTC group presented weak positive, strong positive and moderate positive expression, respectively. The relative expression levels of NF-κB of the sham operation group, ANP group and PDTC pretreatment group were 0.08±0.03, 0.18±0.06 and 0.13±0.04 respectively, and the differences among the groups had statistical significance (all P<0.05). The relative expression levels of CYLD of the three groups were 0.32±0.09, 0.15±0.05 and 0.26±0.08 respectively, in which there was statistical significant difference between the sham operation group and ANP group (P<0.05) and no significant difference between the sham operation group and PDTC pretreatment group (P>0.05). There were negative correlations between the expression of NF-κB and CYLD in the AMs of the ANP group and PDTC pretreatment group (r=–0.708 and r=–0.481, both P<0.05). Conclusion: PDTC can induce the apoptosis of AMs by inhibiting NF-κB activation and enhancing the expression of NF-κB negative regulator CYLD, and thereby ameliorate the lung injury secondary to ANP.