Objective To assess medication literacy status of outpatients and analyze the effect of medication literacy on medication adherence. Methods Outpatients were investigated with Medication Literacy Assessment scale and Medication Adherence Scale in Tianjin Chest Hospital, Tianjin Huanhu Hospital and the Second Hospital of Tianjin Medical University in August 2017. Results The average score of Medication literacy scale of 200 outpatients was 7.60 ± 2.98. There were significant differences among the scores of Medication Literacy Assessment scale of different ages(F=9.444, P＜0.05) and education levels(F=26.682, P＜0.05). Logistic regression analysis showed that medication literacy had an impact on medication adherence in outpatients (P＜0.05). The medication compliance of outpatients with high medication literacy was 2.336 times as high as who with medium medication literacy and 18.529 times as high as who with low medication literacy, and the medication compliance of outpatients with medium medication literacy was 7.925 times as high as who with low medication literacy. Conclusion The medication literacy of outpatients was at the middle level, and most of the outpatients were poor in adherence. The higher the medication literacy level was, the better the medication adherence was; the lower medication literacy level was, the poorer medication adherence was. The medical staff could improve the medication adherence by improving the medication literacy to ensure the health of outpatients.