Concussions are a common traumatic brain injury in soccer games but are often ignored by coaches and athletes. The purpose of our study is to assess the concussion knowledge and attitudes among amateur adolescent soccer athletes in China. Data was collected from questionnaire surveying (Rosenbaum Concussion Knowledge and Attitudes Survey (Student Version)) and semi-structured interviews completed by 69 amateur adolescent soccer athletes who participated in the U17 and U15 male groups of the 2022 China Youth Soccer League. The study followed a mixed methodology cross sectional study design. The concussion knowledge index (0–25) and concussion attitude index (15–75) scores were derived from the questionnaire and descriptive statistics were used for data analysis. The mean score of concussion knowledge is 16.8 ± 2.4 (range 10–22), and the mean score of concussion attitude is 61.3 ± 8.8 (range 45–77). Thematic analysis was used to categorize the participant’s responses of the semi-structured interview and the results were compared with their survey answers of questionnaire. Interestingly, the interviews revealed the inconsistencies between the questionnaire responses and intended behaviors, and multiple factors (injury severity, the importance of the game and substitution rules) influencing concussion-reporting behaviors were identified. In addition, athletes hope to acquire concussion knowledge through formal education. Our study lay the foundation for educational interventions to potentially improve concussion-reporting behaviors among amateur adolescent soccer athletes.