The rapid growth of postgraduate education in China necessitates the imperative to augment the innovative behaviors of postgraduates. The purpose of this study was to explore whether a supportive mentoring style affects the innovative behavior of master's degree students and the potential role that academic aspiration may play in the relationship between the two. A time-lag questionnaire was given to 911 master's degree students in central China for Study 1. The results revealed that a supportive mentoring style positively predicted innovative behavior. Furthermore, the connection between a supportive mentoring style and innovative behaviors was mediated by academic aspirations. Study 2 matched five pairs of students with mentors to administer the survey using semi-structured interviews. The results confirmed the mechanisms through which supportive mentoring styles impact innovative behavior and provided more evidence for them. This study examines the development path of master's degree students' innovative behavior, reveals how internal (academic aspiration) and external (mentoring) factors impact such behavior, and offers insights into graduate students' educational practices.