During the Boxer Rebellion, Xu was the viceroy of Minzhe. Xu, along with Li Hongzhang, viceroy of Liangguang, Liu Kunyi, viceroy of Liangjiang, Zhang Zhidong, viceroy of Huguang, Sheng Xuanhuai, director of the Court of Judicature and Revision, and Yuan Shikai, governor of Shandong, signed the Mutual Protection of Southeast China agreement, openly defying the proclamation of war declared by the imperial court in Beijing against Britain, the United States, France, Germany, Italy, Japan, and Russia, with the aim of preserving peace in their provinces.[10]
As a viceroy, Xu Yingkui was aware of the weaknesses of China when it faces the outer world. He accepted the suggestion of an American diplomat and established the Gulangyu International Settlement. Under the circumstances of a potential Japanese occupation of the island of Gulangyu, Xu started negotiations with the British who were interested in the military value of Gulangyu. To counterbalance the Japanese, Xu was willing to yield the island as an international public settlement. The British government wanted complete separation of the island from Chinese administration, whereas China hoped to maintain nominal sovereignty of the island. The disagreement was eventually taken to the viceroy. Xu waived the sovereignty conditionally, obliging every country which partook in the settlement to provide military protection for the city of Xiamen. The Qing imperial court reviewed his proposal and deleted the article concerning Xiamen, fearing it would open the gates of Xiamen to the foreign powers. On 10 January 1902, the constitution of Gulangyu International Settlement was signed by China, Japan, Britain, the U.S., Germany, France, Spain, Netherlands, Sweden and Norway.[5]
After his retirement, Xu intended to construct a large and luxurious private garden in Guangzhou but died before the plan was carried out.[11]
