Cultivating applied talents is the key focus for most colleges and universities. This paper studies the reforms of "digital signal processing" course, focusing on the cultivation of applied talents. This course is theoretical and abstract. The key problem to be solved in the course is to help students understand the basic concepts and improve their ability to solve practical problems. Combined with practical teaching experience, this paper proposes a set of the teaching theory on cultivating applied talents. The teaching theory enables students to obtain skills from the reform of textbooks, teaching content and methods of examination.