The city of beihai (east longitude 108°50′45″～109°47′28″, north latitude 21°29′～21°55′34″) is located at the southern end of Guangxi and on the northeastern bank of Beibu Gulf. Beihai is only 206 kilometers away from Nanning in the northwest, 198 kilometers away from Zhanjiang city in the east and 147 nautical miles from Haikou city in the southeast. The whole city is surrounded by the sea on the south, north and west side. It has two islands, Weizhou(24.74square kilometers) and Xieyang(1.8 square kilometers) . Weizhou is about 20.2 nautical miles away from the city.

Beihai enjoys a good geographical location. Backed by the great southwest regions (Yunnan, Guizhou, Sicuan provinces) of China, facing Hainan province across the sea, it is the center of the great southwest regions, Hainan and the Southeast Asia, with cities of the Southeast Asia close by. It covers a total area of 3,337 square kilometers , of which the city proper accounts for 957 square kilometers.