Chronic obstructive pulmonary disease (COPD) is a chronic, progressive and lethal lung disease with few treatments. Limax, a mollusk with lung, has been widely used to control phlegm and cough in China, yet whether Limax has a positive effect on COPD is unknown. This study investigated the effects of water-soluble extract from Limax on COPD development and the underlying mechanisms. The results showed that Limax extract improved lung function, relieved emphysema and suppressed the inflammation in the lungs of CS-challenged mice, as evidenced by diminished release of IL-6, KC, TNF-α, IFN-γ, Muc5AC, IL-17 and diminished mRNA expression of Muc5B. Moreover, Limax extract also inhibited phosphorylation of P38 and ERK and increased the expression of PPARγ. More interestingly, Limax extract (0.1 μg/ml) inhibited CSE-induced release of IL-6 in vitro, which was substantially abrogated by heat treatment, and filtrate obtained from the deproteinized Limax extract with the 100 KD ultrafiltration membrane, inhibited the secretion of IL-6. Taken together, these results suggest that, Limax extract prevents COPD development via inhibition of inflammation and mucus production, thus has a potential preventive and therapeutic application in COPD.