This study explores the professional development (PD) of rural teachers in China based on their relationship with "left-behind" children, guided by two research questions: 1) How do rural teachers describe their relationship with left-behind children? and 2) How do rural teachers perceive the influence of their relationship with left-behind children on PD? The study revealed that Chinese rural school teachers experienced complex teacher-student relationships, both positive and negative, with left-behind children. Essentially, this study found that rural teachers are more likely to experience negative, conflict-ridden teacher-student relationships that can be attributed to left-behind children's psychological or behavioural problems, lack of support from parents of rural children, respect and understanding, as well as rural schools' inappropriate educational and management methods. However, the current study is not aimed at criticising the negative impact of teacher-student relationships on rural teachers' PD. Instead, it argues that by reflecting the challenges of teacher-student relationship with regard to left-behind children, rural teachers have become reflective and critically reflective practitioners to improve their PD. This finding enriches the understanding of how teacher-student relationships influence rural teachers' PD, and also provides recommendations from multiple dimensions to enhance these teachers' PD and education.