The construction of case database is the primary link to ensure the successful implementation of case teaching, and it is also an important means to improve the quality of professional degree postgraduate education. Firstly, the necessity of case database construction is put forward through analyzing the teaching goal and teaching situation of the engineering ethics course for professional degree postgraduates in engineering universities. Secondly, the case database of engineering ethics in municipal engineering field is constructed based on the five sub-fields such as water supply engineering, wastewater engineering, building water supply and drainage engineering, water supply and drainage pipe network and ecological restoration of water environment. Finally, the value of case database construction is explored through teaching practice and teaching feedback. Results show that case database of engineering ethics in municipal engineering field promotes the reform of training mode of professional degree postgraduates. It can activate the classroom atmosphere and increase the frequency of mutual interaction between teachers and students. It also promotes students to understand deeply, master theoretical knowledge and apply it to engineering practice flexibly, thereby effectively improving their comprehensive capability of combing theory with practice. Thus, it is of great significance for professional degree postgraduates in municipal engineering field to improve engineering ethics consciousness and fulfill social responsibilities actively. In addition, it can provide references for case database construction and teaching practice for professional degree postgraduates in other majors.