Objective To analyze the predictive value of bispectral index （BIS） dynamic changes for hypotension after laparoscopic surgery in elderly patients with primary liver cancer. Methods 197 elderly patients with primary liver cancer who underwent laparoscopic surgery in the hospital from November 2021 to July 2024 were selected as the research subjects， and all patients received general anesthesia， and their perioperative BIS was monitored. The patients were divided into a hypotension group and a non hypotension group based on the occurrence of hypotension after laparoscopic surgery. The general information and the BIS at 5 minutes before anesthesia induction （T0）， 5 minutes after anesthesia induction （T1）， 30 minutes after the start of surgery （T2） and the end of surgery （T3） in the two groups were compared. The influencing factors of hypotension after laparoscopic surgery in elderly patients with primary liver cancer were analyzed through Logistic regression analysis， and the predictive value of BIS for hypotension after laparoscopic surgery in elderly patients with primary liver cancer were analyzed through receiver operating characteristic （ROC） curve. Results 51 patients were experienced hypotension after laparoscopic surgery among 197 elderly patients with primary lung cancer， and the incidence rate was 25.89%. The proportion of hypertension and operative time in the hypotension group were higher than those in the non hypotension group （P < 0.05）， while the levels of albumin （ALB） and BIS at T2 and T3 were lower than those in the non hypertension group （P < 0.05）. logistic regression analysis showed that hypertension， long operative time， low ALB level， low BIS value at T2 and low BIS value at T3 were all risk factors for hypotension after laparoscopic surgery in elderly patients with primary liver cancer （P < 0.05）. The sensitivity， specificity and area under curve （AUC） of BIS combined prediction of hypotension after laparoscopic surgery in elderly patients with primary liver cancer at T2 and T3 were 92.16%， 78.08% and 0.902% respectively， and the sensitivity and AUC were higher than those single prediction （P < 0.05）， but the specificity was similar to that of single prediction. Conclusion The predictive value of BIS at 30 minutes after the start of surgery and the end of surgery for hypotension after laparoscopic surgery in elderly patients with primary liver cancer are good， and the joint prediction of this two can further enhance the predictive value.