Objective: To identify an optimal magnetic resonance imaging-based classification for evaluating the efficacy of focused ultrasound ablation surgery (FUAS). Design：A retrospective cohort study. Setting: The Affiliated Nanchong Central Hospital of North Sichuan Medical College, Nanchong, Sichuan, China. Population: A total of 643 adenomyosis patients who received FUAS from June 2017 to December 2021. Methods: One-way ANOVA test and chi square test were used to identify an optimal classification for evaluating FUAS efficacy. Magnitude of the optimal classification relating to timing of recurrence in FUAS group was measured by cox regression with hazard ratio (HR) and 95% CI. K-M curve was applied to estimate the medium recurrence time of adenomyosis in the optimal classification. Main outcome measures: The identification of different classifications for FUAS efficacy and the factors contributing to recurrence after FUAS. Results: The rates of dysmenorrhea relief (χ2=10.079, P=0.018) and recurrence could be identified by classification 2 in FUAS group (χ2=10.582, P=0.014), but not in FUAS+ group (P＞0.05). Besides, the recurrence rate in FUAS group (22.2.0%) was higher than that in FUAS+ group (12.1%). Extrinsic subtype in classification 2 (HR=2.315, 95% CI 1.219～4.560, P=0.011) correlated to recurrence of adenomyosis in FUAS group. K-M curve showed that the medium recurrence time of extrinsic subtype (45.2 months) was shorter than that of other subtypes (52.0 months). Conclusions: Classification 2 was the optimal one to identify the rates of dysmenorrhea relief and recurrence. Extrinsic subtype was related to the earlier onset of recurrence after FUAS.