Objective: This paper aims to explore and analyze the analgesic effect of dexmedetomidine combined with ropivacaine retractor tube block after total knee arthroplasty. Methods: The study period was from January 2023 to July 2023. 50 patients admitted to our hospital after total knee arthroplasty were selected as the study subjects, and were divided into the study group (n = 25) and the control group (n = 25) according to double-blind method. The study group was given dexmedetomidine combined with ropivacaine and the control group was given ropivacaine. The analgesic effect and hemodynamic indexes were compared between the groups. Results: At 3 hours postoperatively, the analgesic effects of resting numeric rating scale (NRS) score and activity NRS score between the groups were compared, and the difference was not statistically significant (P > 0.05). At 12 hours and 24 hours postoperatively, the resting NRS score and activity NRS score of the study group were significantly better than those of the control group, and the difference was statistically significant (P < 0.05). Before treatment, hemodynamic indexes such as output per beat, cardiac output, cardiac index, and other hemodynamic indexes were compared between the groups, the difference was not statistically significant (P > 0.05). After treatment, hemodynamic indexes such as output per beat, cardiac output, cardiac index, and other hemodynamic indexes of the study group were significantly better than those of the control group, the difference was statistically significant (P < 0.05). Conclusion: Dexmedetomidine combined with ropivacaine retractor block has better analgesic effect after total knee arthroplasty, and it can be widely used and promoted in the clinic.