Abstract: The concept of signal and system course is abstract, and there are many formulas and properties. The traditional teaching mode leads to students' lack of learning interest, so it is difficult to understand and master the key and difficult points,and it is not easy to form knowledge structure for students. Therefore, a teaching mode of "problem guidance + comparison" is put forward. The teaching mode can not only lead students to think positively and study independently,deeply understand the course knowledge,but also can make students break through the key and difficult points, master the internal relations and characteristics of each knowledge point, construct the knowledge structure, and cultivate the students' ability to discover, raise, analyze and solve problems. In addition, the course evaluation method is reformed, the assessment methods is improved.The process assessment is paid more attentiont to and is focused on students' learning attitude and mastery of the knowledge so as to make the evaluation results more fair and objective. Practice has proved that the teaching mode improves students' learning initiative and learning efficiency.

Key words: Problem-based teaching, Comparative teaching, Signals and systems