Abstract: Previous studies show that Japan was not active and played the least influential role in the negotiation of the surrender of Supao Case prisoners, but this study, which is based on the Archives of Japanese Foreign Ministry reveals that Japan is the first power that Qing government negotiated with, and Japan has its own attitude, which is based much more on the western ideas than following the Britain government, is that Supao Case is a political case, and the prisoners can’t be surrendered to Qing government. Nevertheless, concerning of keeping good relation with Qing government, Japan, who is flexible in its diplomatic strategy, didn’t refuse Qing government directly, and was noncommittal in the diplomatic body in terms of waiting for the instruction from his own government.