Trigeminocardiac reflex (TCR) is a clinical phenomenon that manifests as s sudden onset of hemodynamic perturbations. TCR has been reported in cranio-maxillofacial surgery resulting in severe medical risks. Monitoring the hemodynamic changes during cranio-maxillofacial surgery can provide important information to ensure the continuous evaluation of patient's physical conditions. This prospective observational study was conducted to determine the hemodynamic alterations related to the possibly of occurrence of TCR in patients during dental implant surgery. Methods: One hundred and thirty-five patients (69 males and 66 females) received dental implant placement were enrolled in this study. The hemodynamic changes were evaluated by monitoring heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse oximetry (SpO2). The above data were collected before, during, and after dental implant surgery. Results: The data demonstrated that the minimal values of HR, SBP, and DBP as well as MABP decreased significantly during operation comparing with the corresponding values before operation (p < 0.0001). In addition, HR and SBP decreased significantly in post-operation stage comparing with the corresponding values in pre-operation stage (p < 0.0001). Comparing to dental implant placement in the mandible, patients received dental implant placement in the maxilla had more risks to confront with MABP reduction (OR = 3.98; 95% confidence interval: 1.12–13.2). Conclusion: A significant HR and BP reduction possibly due to TCR can occur during dental implant surgery. Therefore, the dentists should monitor the hemodynamic changes during dental implant surgery to prevent the possible occurrence of medical risks related to TCR.