To evaluate the clinical effect of a new three-phase Chinese medicine (CM) external treatment for acute lateral ankle ligament injuries. From July to December 2023, 64 patients with acute lateral ankle ligament injuries were randomly assigned to receive either the new three-phase CM external treatment combined with the POLICE(protect, optimal loading, ice, compression, elevation) treatment (observation group) or the POLICE treatment (control group), with 32 cases in each group. The observation group consisted of 17 males and 15 females, with an average age of(30.59±3.10) years old ranging from 25 to 36 years old, while the control group included 14 males and 18 females, with an average age of(30.03±3.19) years old ranging from 24 to 37 years old. Visual analogue scale (VAS) evaluation and Figure of 8 measurement were used to evaluate the degree of ankle joint pain and swelling of the subjects at the initial enrollment and after 1 week and sixth weeks of treatment. At the same time, the American Orthopaedic Foot and Ankle Society (AOFAS) and Karlsson Ankle Function Score System were used to evaluate the improvement of ankle joint function in patients at all stages. MRI imaging was employed to observe the degree of biological healing of the anterior talofibular ligament, with the signal to noise ratio(SNR) indicating the level of healing. A lower SNR suggests better ligament healing, as it represents lower water content in the ligament. All patients completed a 6-week follow-up. There was no significant difference in VAS, AOFAS score and Karlsson score between the two groups before treatment (P>0.05). After 1 week and 6 weeks of treatment, the VAS, AOFAS score and Karlsson score of the two groups were significantly improved (P<0.05). After 1 week of treatment, the VAS score of the observation group (3.21±0.87) was lower than that of the control group (4.21±1.50), and the difference was statistically significant (P<0.05). After 1 weeks of treatment, the AOFAS and Karlsson scores [(50.84±4.70) points, (49.97±4.00) points] of the observation group were higher than those [(46.91±5.56) points, (46.66±5.36) points]of the control group (P<0.05). MRI images showed that after 6 weeks of treatment, the SNR value of the observation group was significantly lower than that of the control group, and the difference was statistically significant(SNR of the observation group was 75.25±16.59, the contral gruop was 85.81±15.55), (P<0.05). Compared with the control group, the new three-phase CM external treatment is significantly effective in reducing pain and swelling, enhancing ligament repair quality, and promoting functional recovery of the ankle joint in patients with acute lateral malleolar ligament injuries.