In early 2020, COVID-19 outbroke worldwide. Under the requirement of the Ministry of Education that "teaching and learning never stop under school closure", online teaching has received unprecedented attention. How to ensure the quality of online teaching and ensure the learning effect of students has become the teaching difficulties during the epidemic period. Taking the port channel and coastal engineering specialty of Tongji University as an example, the platform selection, organization arrangement, assessment method, and quality management of online teaching are explored, and the online teaching quality assurance system concerning "platform selection putting emphasis on effect, teaching organization on training, student assessment on process, and practice link on guidance" is put forward. Meanwhile, based on practical teaching, the difficulty in online teaching is summarized and its solutions are found, which can provide reference for online teaching of port channel and coastal engineering specialty in the future.