The aim of this study was to analyze the application of ultrasound-guided low-dose dexmedetomidine combined with lumbosacral plexus block based on artificial intelligence algorithm in the surgical treatment of proximal femoral fractures. 104 patients with proximal femoral fractures were divided into 52 cases in the experimental group (ultrasound-guided lumbosacral plexus block combined with dexmedetomidine based on local fitting image segmentation algorithm) and 52 cases in the routine group (endotracheal intubation and inhalation combined with general anesthesia). An image segmentation algorithm based on local fitting was constructed to enhance the ultrasound image. It was found that in the routine group, the heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) at the beginning of intravenous injection of dexmedetomidine, during skin incision, and half an hour after skin incision were significantly lower than those at admission ( < 0.05). The pressing times of patient-controlled intravenous analgesia (PCIA) in the conventional group (17.05 ± 6.85 times) were significantly higher than that in the experimental group (8.55 ± 4.12 times), and the difference was statistically significant ( < 0.05). The visual analogue scale (VAS) scores at 1, 5, 10, and 15 after operation in the routine group were significantly higher than those in the experimental group ( < 0.05). The number of dizziness, nausea, and vomiting, venous thrombosis of lower limbs, cardiovascular events, and pulmonary infection in the routine group on the 1st, 2nd, and 3rd days after operation were significantly higher than those in the experimental group ( < 0.05). In summary, the ultrasound-guided lumbar plexus-sacral plexus block combined with dexmedetomidine anesthesia based on image segmentation algorithm can effectively maintain the hemodynamic stability of patients, with remarkable analgesic effect and high safety.