Abstract: Objective To investigate the effect of hypertonic conditions induces mucin(MUC)5AC secretion in HBE16 cells, and in which the possible mechanism of PKC-HSP70 pathways. Methods HBE16 cells were cultured in hypertonic saline conditions to induce mucus hypersecretion in vitro. Inhibitors of PKC isoforms were used such as G?6976 (PKCμ inhibitor), Safingol (PKCα inhibitor), LY333531 (PKCβinhibitor) and rottlerin (PKCδ inhibitor) which were served to interference HBE16 cells. HSP70-2 were determined by Western blot analysis. RT-PCR was used to detecte the transcriptional level of HSP70-2. Mucin(MUC)5AC protein content in supernatant were analysed by ELISA. Results The level of HSP70-2, HSP70-2mRNA and MUC5AC proteins werer strongly increased after cells were exposed to hypertonic conditions, and the expression content were increased in a time-dependent manner. (all p < 0.05). The expressions in G?6976 group were significantly lower than that in hypertonic group (p < 0.01) and were still higher than that in control (p < 0.05). Treatment with Safingol, LY333531 and Rottlerin exerted no effects on hypertonicity-induced the content of HSP70-2, HSP70-2mRNA and MUC5AC proteins. Conclusion Hypertonic saline induces the MUC5AC mucin hypersecretion in human bronchial epithelial cells. HSP70-2 mediates hypertonic stress induces mucin hypersecretion through PKCμ dependent signaling pathways.