In order to optimize the anesthesia scheme and improve the effect of surgical treatment, the effects of dexmedetomidine and propofol on postoperative analgesia and cellular immune function of patients undergoing radical gastrectomy for gastric cancer have been analyzed. A total of 86 patients admitted to our hospital from March 2021 to March 2022 who received laparoscopic radical gastritis were selected. The combined dexmedetomidine group (n = 43) and the control group (n = 43) are grouped by the random number table method, respectively. Anesthesia induction regimens of dexmedetomidine combined with propofol and conventional propofol are treated, and the changes in serum stress index, immune function index, analgesia score, and pain score are observed. The results show that the postoperative stress response, analgesic effect, and immune function of patients receiving dexmedetomidine combined with propofol anesthesia are significantly better than those receiving conventional anesthesia, and the incidence of postoperative complications in the dexmedetomidine combined group is significantly lower than that in the control group. The results demonstrate that dexmedetomidine combined with propofol anesthesia intervention has high security in undergoing radical gastrectomy for gastric cancer.