Background: STEM education, which features interdisplines and integration of disciplines, influences the reform of curriculum and teaching, and is reflected in Chinese science textbooks. Purpose: This study aims to analyse how STEM and its integration factors are presented in Chinese science textbooks. Sample: Three sets of high school science textbooks in China, encompass a set of current textbooks nationwide, a set of old national textbooks and a set of old local textbooks, totalling 23 volumes. Each set of scientific textbooks involves physics, chemistry and biology. Design and methods: An evaluation framework was developed to analyse STEM and its integrated content from the distribution of STEM content, types, location, degree of closeness and teaching objectives. Content analysis method was used for STEM and its integrated content. Results: The quantity of science knowledge is the largest, followed by engineering, technology, and mathematics. Physics textbooks are closely related to mathematics, while chemistry textbooks are closely connected with engineering. The STEM integration is more of an integration involving two subjects, which appears in the text most frequently. Conclusion: Although different Chinese science textbooks covered STEM content and its integrated elements, there were differences in publishers and disciplines. The new ideas of science education and curriculum reform can be embodied in science textbooks to update the content.