The content of physics textbooks has always been an important part of physics education research. This chapter systematically reviewed the empirical studies on the contents of physics textbooks from the 1940s to 2022. The brief history and development of research was outlined, and representative research was identified. This chapter reviewed the contents from conceptual, epistemic and cultural levels and the representations of contents in physics textbooks. This chapter also investigates how different content analysis methods contribute to the issues of physics textbooks within the science education community from the methodology perspective. The findings show the researchers' continuous efforts on improving the validity of concepts and readability of texts, growing attentions on nature of science, argumentation and equal issues of hot topics in science educational research. The implications for future research are provided, including the use of new technologies to examine the content of physics textbooks.