<p>Against the backdrop of global educational digitization, exploring the key factors influencing teachers’ intention to continue using digital education platforms is of significant importance. Although existing research has separately identified the impact of teachers’ digital literacy (DL, individual factor) and institutional support (IS, environment factor), their interplay on continuance usage intention (CUI) remains poorly understood. Guided by the individual-environment interaction theory and the technology acceptance model, this study treats DL and IS as two key predictors to investigate their interplay and examines whether their relationship with CUI is mediated by perceived usefulness (PU) and perceived ease of use (PEU). We collected self-reported survey data from a large sample of 9,832 in-service teachers in China and tested the proposed model using PROCESS model 85. The results indicated that DL significantly and positively predicted PEU and CUI, while slightly negatively predicted PU. IS significantly and positively predicted PEU, PU and CUI. The mediating effects of both PU and PEU were established. Additionally, a key finding revealed a significantly negative interplay between DL and IS. Specifically, for teachers with low DL, IS had a stronger positive effect on PEU and further on CUI. Theoretically, we advance the research on teachers’ technology acceptance by integrating individual-environment interaction theory with the technology acceptance model. Practically, these findings advocate for tailored support policies (e.g., differentiated training based on digital literacy) and stratified platform design (e.g., tiered features) to maximize teachers’ usage and platform efficacy.</p>