Objective To study the effect of mechanical stretch on expression of inflammasome related factors in human periodontal ligament cells (HPDLCs). Methods HPDLCs were subjected to mechanical stretch with a 20% elongation magnitude for 6 h or 24 h, respectively. The mRNA and protein expression levels of IL-1β, Caspase-1 and NLRP3 were detected by real-time quantitative PCR and Western blot. The levels of IL-1β in the cell-culture medium of HPLCs in response to mechanical stretch for 1, 2, 4, 6 h were detected by ELISA, respectively. In control group, HPDLCs were cultured in similar conditions but not subjected with stretch. Results The mRNA and protein expression levels of IL-1β, Caspase-1 and NLRP3 were up-regulated with mechanical stretch for 6 h (P<0.05). The protein expression level of NLRP3 was up-regulated with mechanical stretch for 24 h (P<0.05). Compared with control group, the content of IL-1β in the cell-culture medium of HPLCs was increased significantly in response to mechanical stretch for 4 h and 6 h(P<0.05). Conclusions The expression of NLRP3/Caspase-1/IL-1β related factors in HPDLCs can be induced by 20% mechanical stretch for 6 h.