ABSTRACT This research aims to investigate gender representation in China’s most popular English language textbooks used in secondary schools. The study examines potential gender biases and stereotypes presented in the materials and investigates their impact on students’ gender identity formation, particularly how they affect female under-representation or sexism in the classroom. To accomplish this, we conducted content analysis of the top ten versions of English language textbooks used in Chinese secondary schools. Our analysis focused on various aspects such as titles, family relationships, physical surroundings, appearance, professions, social engagements, and order of mention. We created a Textbook Gender Bias Index (TGBI) to assess the presence and severity of gender bias in these areas. Our findings reveal that potential gender bias in textbooks correlates significantly with the economic status of the area using that version. Based on our results, we recommend ensuring fair gender representation in educational materials and instructional approaches to prevent biassed gender portrayal, which is crucial for promoting inclusive education in the language classroom. This study provides valuable insights into how gender representation in language textbooks can influence gender identity formation and offers practical recommendations for educators and textbook publishers to make language learning more inclusive.