Objective To explore the early warning role of high-frequency ultrasonography on knee joint military training injury (MTI).Methods A total of 80 newly recruited soldiers from an armed police force were enrolled. All of them received standardized recruit training, and underwent high-frequency ultrasonography of both knee joints, clinical inquiry and physical examination before and after 3-month recruit training.Results All the 80 recruits were male, with an average age of (20.4±1.4) years old, in good physical condition, and there was no chief complaint of knee discomfort before recruit training. Ultrasonography of both knee joints before recruit training showed osteochondrosis of the tibial tuberosity in 4 cases (4 knee joints, including 1 case complicated with old injury of patellar tendon), patellar tendinopathy in 2 cases (2 knee joints), old tendinopathy at the end of iliotibial tract in 2 cases (2 knee joints), old injury at the end of lateral collateral ligament in 1 case (1 knee joint), and suprapatellar bursa effusion in 2 cases (2 knee joints). After 3-month recruit training, 3 of the 4 recruits with osteochondrosis of the tibial tuberosity developed knee joint pain, and 2 of them had significant pain (1 case complicated with old injury of patellar tendon), which affected normal training. Knee joint pain was found in the 2 cases with patellar tendinopathy, of which 1 case had significant pain affecting normal training. No complaints of discomfort were reported in the 2 cases with old tendinopathy at the end of iliotibial tract, 1 case with old injury at the end of lateral collateral ligament, or 2 cases with suprapatellar bursa effusion.Conclusion High-frequency ultrasonography can find the knee joint MTI of asymptomatic soldiers, which is helpful for early development of prevention and control strategies, and is of great significance for maintaining the health of soldiers and improving the combat effectiveness of troops.