This study adopts the action research method to understand the impact of online teaching on the learning outcomes of working nursing students using the “Infection Control in Nursing Practice” course as the research context. The research design focuses on the learning activity process of online teaching. The study subjects consisted of 55 working nursing students, aged 25-55 years old, all of whom were taking the online courses for the first time. The results of the study show that the semester grades of online teaching courses were better than those of physical courses and the length of important learning activities such as audio-visual materials (AVMs) would best be produced within 5-12 minutes, while the key points of each section would best be explained within 5 minutes of the beginning of the AVMs. Working students may miss out a variety of online learning activities, so a reminder mechanism should be planned to prevent students from missing out learning activities. The teachers are facilitators and advisors in online teaching, so they may plan time outside of learning activities, such as office hours, to provide a channel for student consultation. The results of this study can be used as a direction to improve the subsequent online teachings and provide a reference for other teachers to implement online teaching.