Objective To investigate the impact of goal-directed therapy guided by the Hypotension Prediction Index （HPI） on intraoperative hypotension and postoperative acute kidney injury （AKI） in elderly patients undergoing pulmonary surgery. Methods A total of 144 elderly patients who underwent pulmonary surgery and were admitted to our hospital from March 2024 to June 2025 were selected and divided into a conventional group （72 cases） and a study group （72 cases） using the random-number table method. The conventional group received routine blood-pressure monitoring and management， while the study group implemented HPI-guided goal-directed therapy. The perioperative blood-pressure variations， intraoperative hypotension （IOH） profiles ［including incidence， total duration， and time-weighted average of hypotension （TWAH）］， dosages of vasoactive agents （dobutamine and norepinephrine）， and postoperative outcomes ［incidence of AKI， intensive care unit （ICU） stay time， and postoperative hospital stay］ were compared between the two groups. Results Finally， a total of 141 patients were recruited for the study， with 70 in the study group and 71 in the conventional group. Fifteen minutes after one-lung ventilation， during pneumonectomy， and at the time of chest closure， the systolic blood pressure and mean arterial pressure in the study group were higher than those in the conventional group， and these differences were statistically significant （P < 0.05）. The incidence of intraoperative hypotension and the value of TWAH in the study group were 17.14% and （0.25 ± 0.06） respectively， which were lower than 32.39% and （0.37 ± 0.11） in the conventional group， and the differences were statistically significant （P < 0.05）. The dosages of dobutamine and norepinephrine in the study group were greater than those in the conventional group， and the differences were statistically significant （P < 0.05）. The incidence of postoperative AKI in the study group was 1.43%， which was lower than 11.27% in the conventional group， and this difference was statistically significant （P < 0.05）. The total duration of hypotension， ICU stay time， and postoperative hospital stay in the study group were shorter than those in the conventional group， and the differences were statistically significant （P < 0.05）. Conclusions The goal-directed therapy guided by HPI can mitigate intraoperative blood pressure fluctuation， lower the incidence and severity of intraoperative hypotension， diminish the occurrence of postoperative AKI， and facilitate postoperative recovery in elderly patients undergoing pulmonary surgery.