Abstract: [Abstract] Objective To study the expression of GRP78 and BCL-2 in ameloblasts of fluorosis rats and to explore the injury diversity of fluoride to ameloblasts at different stages. Methods 20 wistar rats were selected and fed with fluoride water. 8 weeks later, they were sacrificed and immunohistochemistry and HE staining were used to detect the changes of ameloblast and the expression of GRP78,BCL-2 in rat incisors. Metamorphic microscope images analysis system and spss13.0 software were used to analyze the data. Result The expression of GRP78 in ameloblast secretory and secretory phase was higher than that in transformation period and mature period. BCL-2 had the highest expression in secretory phase and transition period,however, it declined in secretory stage and mature stage. The differences between groups were statistically significant.(P<0.05） Conclusions The injury of fluoride to ameloblasts at different times is different.