Background: Different treatments with varying clinical efficacies have been applied to treat knee osteoarthritis (KOA). This study observes the effectiveness of deep hyperthermia combined with dynamic traction in KOA treatment. Methods: Deep hyperthermia and dynamic traction was administered to 60 patients with KOA. The pretreatment and 20- and 40-day post-treatment visual analog scale (VAS) and Lysholm score, knee joint cavity effusion, synovium thickness, and synovial blood flow signal (by high-frequency ultrasound) of the patients were recorded. The pretreatment and 20- and 40-day post-treatment Lysholm scores were 47.17 ± 5.07, 63.22 ± 3.44, and 81.98 ± 3.30 (P < 0.001), respectively. Results: The pretreatment and 20- and 40-day post-treatment VAS scores were 5.67 ± 0.91, 2.92 ± 0.81, and 0.60 ± 0.72 (P < 0.001), respectively. The pretreatment and 20- and 40-day post-treatment articular effusion was 5.41 ± 0.46 mm, 4.34 ± 0.34 mm, and 2.32 ± 0.32 mm (P < 0.001), respectively. The pretreatment and 20- and 40-day post-treatment synovial thickness was 3.44 ± 0.31 mm, 2.79 ± 0.15 mm, and 2.32 ± 0.32 mm (P < 0.001), respectively. The pretreatment and 20- and 40-day post-treatment grades of synovial blood flow signal exhibited a significant difference (P < 0.001). Conclusion: Deep hyperthermia combined with dynamic traction can significantly improve the clinical symptoms and pain degree in KOA, reduce joint cavity effusion, synovium thickness, and internal blood flow, and the effect improves with time. The changes in soft tissues observed by high-frequency ultrasound are reliable and consistent with clinical signs.