Background Ventilator-associated pneumonia (VAP) is a common and severe hospital-acquired infection, and oral care is an effective preventive measure. However, the compliance and quality of oral care among intensive care unit (ICU) nurses need improvement. Methods This quasi-experimental study was conducted in two ICUs at the first affiliated hospital of Gannan Medical University, Ganzhou, China, involving 74 ICU nurses. The participants were allocated to either a micro-course education group or a conventional education group. Of these, 32 nurses were from the General ICU, and 42 were from the Cardiac ICU. Both groups received oral care education, with the micro-course group receiving video-based instruction, and the conventional group receiving PowerPoint-based training (Microsoft® Corp., Redmond, WA, USA). Data on oral care compliance and levels of Knowledge, Attitudes, and Practices (KAP) were collected at baseline and during follow-ups over one month. Statistical analysis was conducted using a mixed-effects model to compare outcomes between the groups, highlighting variations in ICU nurses' oral care practices across different ICU settings. Results Both education methods had statistically significant effects. The micro-course education group showed earlier and more pronounced improvements in oral care compliance. Quantitatively, the micro-course group experienced a mean increase in compliance of 0.281 (p = 0.032) at the third follow-up, whereas the conventional group saw a mean increase of 0.261 (p = 0.042) at the fifth follow-up. Additionally, KAP levels in both groups improved significantly (p < 0.001). Conclusion This study demonstrates that micro-course education has a statistically significant impact on ICU nurses' oral care compliance and levels of KAP in the short term. Although there was no significant difference in oral care compliance between the micro-course and conventional education methods, the micro-course showed certain advantages in teaching quality. Long-term studies are needed to evaluate the sustainability of these improvements. Promoting micro-course education in ICU nursing practice may enhance oral care practices and potentially reduce the incidence of VAP.