The software human resources should have not only the informational professional competencies but also the key competencies. Teachers of information science had better use effective teaching methods to enhance both competencies for students concurrently. Problem based learning (PBL) uses the existing problems in life as key factors to drive learning. It emphasizes on the independent learning and cooperative learning to construct the subject area knowledge and the key competencies. This paper aims to explore the definitions, characteristics, models, environments, and problems of PBL. The feasibility of teaching information science using PBL is also discussed. It may help to enhance the information professional competencies and the key competencies. At last, three teaching problems have been designed that can be as references for information science teachers.