Objective: To explore the clinical efficacy of ultrasound-guided drug delivery of diclofenac diethylamine emulsion combined with rehabilitation training in the treatment of elbow ossifying myositis (EOM), and to provide evidence-based support for clinical treatment. Methods: 86 patients with elbow ossifying myositis admitted to the orthopedics department of our hospital from January 2022 to December 2023 were selected as the study subjects. They were divided into a control group (43 cases) and an observation group (43 cases) using a random number table method. The control group received rehabilitation training only, while the observation group received ultrasound-guided drug delivery of diclofenac diethylamine emulsion in addition to the rehabilitation training. Both groups were treated continuously for 8 weeks. The range of motion (ROM), visual analogue scale (VAS) for pain, and Mayo Elbow Performance Score (MEPS) were compared between the two groups before and after treatment, and adverse reactions were recorded. Results: Before treatment, there were no statistically significant differences in elbow ROM (flexion, extension, pronation, and supination angles), VAS score, and MEPS score between the two groups (P>0.05). After 8 weeks of treatment, the observation group had significantly better elbow flexion angle (115.23±10.56)°, extension angle (-5.12±2.34)°, pronation angle (78.45±8.12)°, and supination angle (75.36±7.89)° compared to the control group's (92.67±9.87)°, (-12.34±3.12)°, (65.78±7.56)°, and (62.13±6.98)°, respectively (P<0.05). The VAS score of the observation group (1.23±0.56) was significantly lower than that of the control group (3.56±0.89) (P<0.05). The excellent and good rate of the observation group was significantly higher than that of the control group (P<0.05). There was no statistically significant difference in the incidence of adverse reactions between the observation group (4.65%) and the control group (6.98%) (P>0.05). Conclusion: Ultrasound-guided drug delivery of diclofenac diethylamine emulsion combined with rehabilitation training can effectively improve joint mobility, reduce pain, and enhance elbow function in patients with elbow ossifying myositis. This treatment approach is safe and worthy of clinical promotion and application.