Abstract: Environmental hygiene is an important branch of preventive medicine, and the study of this course is crucial for cultivating the professionals of applied preventive medicine in the new era. Since the outbreak of COVID-19, the new mode of "online+offline" teaching and "the important role of environmental sanitation in the prevention and control of infectious diseases" have provided new ideas for the teaching reform of this course. In the face of the new situation and new changes, and in order to meet the needs of the development of undergraduate preventive medicine education, this article discusses the teaching reform of environmental hygiene for undergraduates in colleges and universities under the context of infectious diseases by combining with the characteristics of environmental hygiene, optimizing the teaching content of environmental hygiene courses, deepening the reform of teaching methods, promoting the learning outcome of students and improving the comprehensive quality of students.