The Xiyu East Fort is also known as the Dongtai Fort. During the Guangxu period of the Qing dynasty, new coastal defense fortifications were built on West Island but they were short of the latest artillery pieces. Thus, when French forces attacked the West Island during the Sino-French War, defenders could not return fire, and the West Island and Magong fell to the French. The French withdrew from Penghu after reaching an agreement with the Qing court. Taiwan governor Liu Mingchuan repeatedly submitted requests to strengthen Penghu’s coastal defenses. In 1887, the construction of four forts began under Liu’s supervision; the Xiyu East Fort was one of them.

In March 1896, a year after the Sino-Japanese War, Japanese forces attacked Penghu. The Xiyu East Fort unleashed its firepower, resulting in many Japanese casualties. The Japanese military held the fort during the occupation, adding new facilities. After World War II, Chinese Nationalist forces took over and constructed some military dormitories. The army started withdrawing when the Ministry of the Interior designated the Xiyu West Fort as a national historic monument in 1985. However, the military maintained a presence at the Xiyu East Fort even after it was classified as a national historic monument in 1991. In 2012, it was finally handed over to the Penghu County government.

The fort has a square layout. Above the outer gate, Liu Mingchuan’s inscription reads “Xiyu East Fort.” A trench between inner and outer fortifications serves as a buffer zone. The main structure blends masonry and concrete, and a layer of that era's latest type of cement covers the exterior walls. In addition to artillery batteries, the facility houses a wardroom, large barracks, secret passages and ammunition depots. Although smaller than the Xiyu West Fort, this installation is vital to the coastal defense.