Taking the water quality testing of local natural resources West Lake as the experimental content of the chemical experiment elective course, students experience through the entire elective course in the role of "water quality inspector". The chromaticity, turbidity, PH value, ammonia nitrogen content, permanganate index and hexavalent chromium content of water in West Lake were measured. The middle school students in the course experience the work of "water quality inspector", have a clear understanding of the profession, and lay the foundation for future career choices. The course takes chemical experiments as the carrier, focuses on solving practical problems with book knowledge, and improves students'' ability to operate experiments. The unusual professional experience really puts the core literacy of chemistry into practice.