Abstract: Objective To establish a comprehensive evaluation index system on methadone maintenance treatment (MMT) service in China and determine the weight coefficients of the indexes at all levels. Methods Delphi method was used to screen the indexes, and Fuzzy comprehensive evaluation method, to calculate the weight coefficients. Results Eighteen experts with three years and above relevant experience on MMT were selected for counseling. Their average age was 37.78 years, and on average, had 5.28 years of working experience in MMT-related field. The motivation coefficients of experts in two rounds of counseling were 94.7% and 100.0%, respectively. Both of the authorization coefficients are 0.80. The coordination coefficients of experts for the four-level indexes are 0.41, 0.36, 0.30, and 0.32 in the first round, and are 0.71, 0.58, 0.51, and 0.47 in the second round, respectively. Through two rounds of counseling, 7 indexes at the first level, 23 at the second level, 63 at the third level, and 41 in the fourth level were finally established. Of the first-level indexes, medical service provision had the greatest weight (0.160 4), followed by the medical record management (0.154 9). Of the second-level indexes, establishing a coordinating mechanism between MMT clinics and drug control agencies weighted the greatest (0.071 0). Conclusion The evaluation index system on MMT service established in the study is comprehensive and reliable, and can provide a reference for construction and assessment of comprehensive evaluation index system on MMT service in China.