This study examined teachers’ and students’ perceptions of the factors influencing grading fairness in blended learning. Semi-structured interviews were conducted with teachers and students in Chinese universities. Social cognitive theory (SCT) was used to examine how personal and environmental factors shape students’ perceptions of fairness in the grading process. Both teachers and students have emphasized that grading fairness is greatly influenced by personal and environmental factors in blended learning. Teachers and students emphasized that factors like scores and transparent grading criteria had an influence on their perceived fairness. There are also some differences between students and teachers. Specifically, teachers placed less emphasis on class interaction and the teacher-student relationship, while only students mentioned student peer assessment. Technology support, emphasized by teachers, was not recognized by students. Student factors were less prominent than teacher and environmental factors. The study identified more hindering factors than facilitating factors, suggesting that teachers must exert effort to achieve grading fairness.