Objective: To investigate the pathological changes of placenta and its relationship with pregnancy outcome. Methods: The clinicopathological data of 80 cases of amniotic fluid stained placenta and 80 cases without amniotic fluid stained placenta were collected. The pathological changes of placenta under microscope in the two groups were observed, and the relationship between pathological changes and pregnancy outcome was analyzed. Results: Compared with the control group, the change in the observation group (placenta chorioamnionitis, syncytiotrophoblast nodules increased, villous interstitial fibrosis incidence rate) were more obvious, the difference was statistically significant (P<0.05); the incidence rate of the adverse pregnancy outcomes in the observation group (fetal distress, neonatal asphyxia, aspiration pneumonia, etc.) was higher than that in the control group, the difference was statistically significant (P<0.05). Conclusion: The pathological changes of placenta with meconium stained amniotic fluid are closely related to the adverse pregnancy outcome. Routine examination of placental pathology in meconium stained amniotic fluid can guide the diagnosis and treatment of maternal and neonatal diseases.