Objective: To discuss the influence of medullary cavity washing and filling with mixed liquor of low-concentration epinephrine and normal saline (NS) (1∶500 000) on vital signs and bone cement implantation syndrome (BCIS) in the process of total hip replacement (THR). Methods: One hundred and fifty-two patients intending to have THR were divided into an observation group (76 patients) and a control group (76 patients) randomly. The control group adopted NS for washing and gauze for filling the marrow cavity, while the observation group adopted the mixed liquor of low-concentration epinephrine and NS for washing and adopted gauze for filling the marrow cavity. The changes of vital signs and BCIS occurrence rate of the patients of two groups occurring after medullary cavity washing and filling (T0), during bone cement filling (T1), 5 min after filling (T2) and 10 min after filling (T3) were collected and compared. Results: The heart rate, systolic pressure, fingertip blood oxygen saturation degree of patients of the observation group at T1 and T2 were evidently higher than those of the control group (P<0.05). As indicated by the repeated measuring variance analysis results, the inter-group effect, time effect and interaction effect of heart rate, systolic pressure, fingertip blood oxygen saturation degree of the two groups at different time points were of statistical significance (P<0.05); the time effect of diastolic pressure and central venous pressure was of statistical significance (P<0.001). The occurrence rates of respiratory distress, hypoxia and hypotension shock of the observation group were evidently lower than those of the control group (P<0.05). Conclusion: The medullary cavity washing and filling with low-concentration epinephrine helps maintain stable vital signs of the patients in bone cement implantation and reduce the occurrence rate of BCIS. The method can positively enhance the operation safety of THR patients.