Hydrobiology is a fundamental course for undergraduate majors in environmental science.The teaching team of hydrobiology at Yangzhou University has gradually formed a teaching mode that combines course teaching with subject competitions,using subject competitions as the starting point.By exploring the integration points between course content and subject competitions,and building a"three classroom"practical platform,it has stimulated students'learning interest,effectively improved their practical skills and innovation ability,and achieved high-quality competition results in various levels of subject competitions,effectively improving the teaching quality of hydrobiology courses.