PurposeThis research aims to discover the relationship between social media usage (SMU) and the critical thinking ability (CTA) of university students, and to answer the question that whether social media dependence (SMD) affects the development of CTA, and thus providing a reference for the social media access strategy of academic libraries from the perspective of media information literacy.Design/methodology/approachThe research data were collected via 300 valid questionnaires whose respondents are students from three universities in China. Multistage stratified cluster sampling method was used to select the respondents, which guarantees statistical representativeness. A pre-test was conducted to ensure the validity of the questionnaire.FindingsIt is shown that the total score of CTA and the six sub-dimensions are significantly positively correlated with SMU, but strongly negatively correlated with SMD. Based on the mediating effect testing, it is discovered that the degree of SMD can affect the promoting relations between the usage intensity of social media (UISM) and CTA. Clearly, SMU is a double-edged sword. While it narrows the digital gap in terms of accessibility, it widens the digital gap in terms of usage.Originality/valueThe differences in SMU have a significant impact on the development of CTA of university students. This inspires us to consider the ability of “using social media in a balanced way” as an important evaluation and training direction when inquiring media literacy. As social media is becoming a critical channel in cultivating individual's thinking skills, it is highly suggested that the amount of time spent on reading fragmented information on the internet should be controlled.