understandable method could be designed，it is useful for teaching physics for liberal arts. In this paper，an easy-to

-understand teaching method about the entropy is proposed. Therefore，the concept of entropy can be taught without

the needing for students to learn the second law of thermodynamics. The corresponding teaching design is as　follows: introducing the concept of entropy ( namely，Boltzmann entropy) through daily life examples，designing two examples for students to calculate the entropy，making students fully understand the meaning of entropy through discussion on specific problems，obtaining the Clausius entropy from Boltzmann entropy through an example，designing an entropy demonstration experiment to strengthen teaching effect，and connecting the entropy with environmental protection to make physics humanistic，and finally specifying the different levels of entropy calculation. Problem-based learning ( PBL) is adopted in the teaching design.