Abstract: With the development of new technologies in the discipline, changes in the new era students'abilities, interests, learning environment, learning methods, and employment environment, many problems have gradually emerged in the teaching construction process of the course building water supply and drainage engineering. This article focuses on the reform and practice of online and offline blended teaching, and explores the methods and methods of blended teaching. After two rounds of mixed online and offline teaching practices, it has effectively solved some of the existing drawbacks, improved teaching quality and educational effectiveness.

Key words: Building water supply and drainage engineering, Online and offline, Mixed teaching, Flipped classroom, Teaching effect, Teaching reform