Objective To observe the clinical manifestations of airborne troops with lateral collateral ligament injury of ankle joint, and to explore the diagnosis and prognosis evaluation value of high-frequency musculoskeletal ultrasound. Methods A total of 120 patients with suspected lateral collateral ligament injury of ankle joint caused by airborne training in General Hospital of PLA Central Theater were enrolled between January 2021 and January 2023. The clinical manifestations of patients were observed, and all completed examinations of high-frequency musculoskeletal ultrasound and magnetic resonance imaging (MRI). Taking MRI or intraoperative exploration as reference standards, the consistency between high-frequency ultrasound and the reference standards was analyzed by Kappa consistency test. All patients were followed up for 6-8 weeks. The prognosis was evaluated by scores of American Foot and Ankle Association (AOFA). The relationship between measurement parameter [anterior talofibular ligament (ATFL) thickness] and prognosis was analyzed. Results It was confirmed by MRI or intraoperative exploration that there were 114 cases with lateral collateral ligament injury of ankle joint, including 36 cases at grade I, 32 cases at grade II (12 mild cases, 20 severe cases) and 46 cases at grade III. The sensitivity, specificity, accuracy and kappa value of high-frequency ultrasound in the diagnosis of lateral collateral ligament injury of ankle joint were 98.25%, 83.33%, 97.50% and 0.756, respectively. There was no significant difference in diagnosis results of disease severity grading between high-frequency ultrasound and the reference standards (P>0.05). According to AOFA scores, there were 92 cases in good prognosis group and 22 cases in poor prognosis group. After treatment, ATFL thickness in good prognosis group was thinner than that in poor prognosis group (P<0.05). ATFL thickness measured by high-frequency ultrasound and MRI was of good prognostic value in lateral collateral ligament injury of ankle joint, but there was no significant difference in AUC between the two methods (P>0.05). Conclusion The main grading of lateral collateral ligament of ankle joint caused by airborne training is grade III in airborne troops. The consistency between high-frequency ultrasound and intraoperative exploration is good in the diagnosis of lateral collateral ligament injury of ankle joint, and which has certain prognostic value.