This study aims to propound an instructional design for a service-learning course grounded in public problem analysis and verify its immediate and sustained outcomes through the actual instructional process. A quasi-experimental research design was adopted wherein students who were enrolling in a service-learning course were considered as a treatment group, while those not enrolling in the course were categorized into a comparison group. Three-wave surveys were distributed at the beginning, end, and 6 months after the end of the course. Our difference-in-differences (DID) analysis showed that the project-based service-learning experience seems to be negatively related to perceived problem-solving ability but positively associated with students' public service motivation (PSM) in the short term. However, the above influence did not sustain as time progressed. This study helps to clarify the relation between service-learning courses and students' problem-solving ability as well as PSM in the field of public affairs education. It can also serve as a foundation for efforts to improve subsequent instructional plans of service-learning courses.