Shifting from quantity expansion to quality and efficiency improvement is an important proposition for connotative development of overseas postgraduate education in China. This study focuses on teacherstudent interaction, puts forward the concept of supervisors′ intercultural adaptive guidance, and explores process mechanism and boundary condition of supervisors′ intercultural adaptive guidance affecting academic achievements of international postgraduates. Empirical results show that supervisors′ intercultural adaptive guidance positively affects academic achievements of international postgraduates through cognitive and emotional mediation paths. Deeplevel cultural distance weakens the relationship between supervisors′ intercultural adaptive guidance and academic selfefficacy; deeplevel and surfacelevel cultural distance enhance the relationship between supervisors′ intercultural adaptive guidance and interaction comfort. To improve supervisors′ intercultural adaptive guidance ability, supervisors should adjust their guidance behaviors to adapt to cultural particularity of international postgraduates, pay attention to the cognitive and emotional state of their students, and grasp the cultural distance situation. Institutes of cultivating international postgraduates should provide assistance and support, build a comprehensive interactive support system between supervisors and international graduates, improve process management, and provide training opportunities for supervisors.