Objective：The dental pulpitis model of α7 nAChR gene knockout mice was established to provide an experimental model for studying the mechanism of α7 nAChR in the occurrence and development of dental pulpitis. Methods：Sixteen α7 nAChR knockout mice（knock out，KO）and 16 wild type（wild type，WT）in C57BL/6 were selected，and a hole was drilled on the maxillary first molars to expose dental pulp to constructed dental pulpitis model. The mice were sacrificed on 1 day，3 days，7 days after operation respectively. HE staining and immunohistochemistry were carried out for detecting NOD-like receptor protein 3（NLRP3）. Results：HE staining showed blood congestion and tissue edema around the medullary foramen in α7 nAChR KO mice and WT mice at 1 day after medullary cavity exposure. On 3 days after the exposure of the dental pulp cavity，the inflammatory cells were aggregated，reached to the bottom of the crown pulp in α7 nAChR KO mice，while were mainly around the perforationin the pulp tissue in WT mice. On 7 days，pulpitis cells of α7 nAChR KO mice were infiltrated into root pulp，while inflammatory pulp cells of WT mice were still concentrated mainly in the crown pulp. The expression of NLRP3 in pulpitis of α7nAChR KO mice was significantly higher than that of WT mice by immunohistochemical staining（P < 0.05）. Conclusion：The pulpitis model of α7 nAChR gene knockout mice was successfully constructed，and the pulpitis infiltration of α7 nAChR gene knockout mice was significantly faster than that of WT mice.