round 1644, when Qing completed the occupation of Beijing, there were remarkable changes in the relationship between Joseon-Qing. The heavy ‘Annual Tribute Payment’ imposed on Joseon was greatly reduced, and Crown Prince Sohyeon, who had been held as a hostage, returned to Joseon. In addition, regular envoys to the Qing were also integrated once a year, and the amount of gift provided for Qing envoys was also reduced. The Joseon-Qing relationship, which had been characterized bya series of tensions and conflicts, seemed to begin stabilizing from Ming-Qing Transition.BR Existing studies have consistently focused on Qing’s “Enterting the Pass” as a decisive factor in these changes around 1644. In fact, the Ming fall and the Qing conquest of China removed major variables in the Joseon-Qing relationship. At that time, regency Dorgon also decided to send Crown Prince Sohyeon back to Joseon, and cited the Qing conquest of China as the reason. In other words, since then Qing’s “Enterting the Pass” has been pointed out as a marked watershed in the Joseon-Qing relationship, and Crown Prince Sohyeon’s return has been regarded as supporting the idea.BR However, the changes in the Joseon-Qing relationship are not explained by “Enter the Pass” alone. This is because that began in 1643, a year before “Entering the Pass” by Qing. Therefore, I think there was another variable worth our attention, other than “Enter the Pass” against a background of the conversion of the Joseon-Qing relationship. In this study, it is the regency of Dorgon that is presented as the keyvariable.BR After Hong Taiji’s death in 1643, Dorgon, who seized power in an unusual way, used Joseon to extend his power base. Immediately after Dorgon became regent, he planned and realized Crown Prince Sohyeon’s second return. It was to strengthen ties with Crown Prince Sohyeon, the next heir to the throne of Joseon. Crown Prince Sohyeon’s second return was to show Dorgon’s strategy for Joseon in advance. After “Entering the Pass,” Dorgon tried to augment his influence in Joseon by permanently returning Crown Prince Sohyeon. The challenge of getting adequate compensation for his investment has begun.