In response to the 2001 National curriculum review in China, which explicitly promotes scientific inquiry in science-related subjects, many editions of new textbooks were published. Among them, this study explored the quality of scientific inquiry in the most popular science textbooks. There are nine sets of high school science textbooks published by seven major Chinese publishers in this study. Through the content analysis of these textbooks, it is found that all the textbooks included the specific sections dedicated to scientific inquiry. The quality of scientific inquiry in these textbooks was explored on specific aspects including relevance to daily life, the explicit teaching guidance, the complete inquiry process and the openness of inquiry. The findings suggest that 53% of inquiry activities included close connections to daily life. However, there were very few textbooks providing explicit teaching guidance. In particular, regarding the inquiry process of "results implications" and "making new inquiries", 4% and 9% of inquiry activities in the textbooks came with explicit teaching guidance. Moreover, most of the activities lacked the process of scientific inquiry, especially at the stage of "questioning". The findings are also in accordance with other literature that states that most textbooks lack high-level, open-ended inquiries. This study suggests that science textbooks should include more relevant scientific inquiries with explicit teaching guidance, opportunities for students to experience the complete inquiry process and more student autonomy in conducting inquiry.