On June 15 of the third year's reign of Emperor Yong Le (namely on July 11, 1405 AD), Zheng He was ordered to head a fleet to sail to the western seas with the aim of "making an exhibition of prowess and prosperity of China to other countries."

　　Zheng He led a large fleet comprising of 208 ships and a contingent of more than 27,800 officers and men to set to sea from the port of Longjiang in Nanjing, via Liujiawan in Taichang, Jiangsu Province, where they assembled and got into formation and sailed towards the Port of Taiping in Changle County, Fujian Province, where they waited for the rise of northeast monsoon. As soon as the winter set in and northeast monsoon rose, Zheng He's Fleet sailed formally from Wuhumen near the estuary of the Minjiang River in Fujian Province. After crossing the western coastal waters of the South China Sea, the fleet first arrived at Qui Nh?n in Vietnam, and then the Java Island in Indonesia, Malacca in Malaysia and the Sumatra Island in Indonesia. Afterwards, the fleet set off from the Sumatra Island and sailed across the Bengal Bay in the India Ocean to reach Sri Lanka. Then, it skirted the Indian Peninsular and arrived at Quilon, Cochin and Calicut of India.

　　After a short period of rest and reorganization, Zheng He's Fleet left Calicut and returned to China. When the fleet arrived at the Old Port in the Sumatra Island, Chen Zuyi, a ringleader of pirates, pretended to accept the amnesty and pledged loyalty to the ruler of the Ming Dynastry, secretly gathered some 5,000 pirates and launched a surprise attack against Zheng He's fleet. Zheng He's Fleet, which combined peacetime footing with wartime footing all the time, was always on high alert and immediately fought back. It was the first battle the fleet had ever fought during the voyage, and the officers and men wiped out all the pirates, and captured Chen Zuyi and other two ringleaders, who were later escorted back to China and executed. This sea battle removed nearly all pirates roaming in the waters in Southeast Asia, and had thus ensured the safety of maritime transportation and the well-being of the people in that area, thus Zheng He's Fleet was warmly praised by the countries in that area.

　　On Sept. 2 of the fifth year's reign of Emperor Yong Le (Oct. 2, 1407), the fleet returned to China safely.

　　Zheng He's first voyage was a large-scale explorative voyage, which was conducted after careful preparations, and his voyage preceded Christopher Columbus' discovery of America by 87 years, Portuguese Fleet's arrival at Calicut of India in 1497 headed by Vasco da Gama by 92 years, and Magellan's start of its global navigation in 1519 by 114 years. The voyage was really an unparalleled feat in world navigation history in terms of the number of ships involved, the voyage distance, duration of sailing, the displacement of ships and number of sailors involved, seamanship, shipbuilding technologies and the sophistication of its maritime equipment. Additionally the fleet had powerful fighting capability, by which it wiped out all invading pirates in its first battle, which had greatly enhanced the prestige of the Chinese nation. The success of Zheng He's first voyage had not only accumulated rich navigational experience, but also built up China's prestige in the South Asia, creating an important peaceful environment for China and laid a solid foundation for the voyages later.