Nankai District borders the Hai River in the east and Chentangzhuang Railway in the west and south.

The Tianjin New Technology Industrial Area, a 12 square km precinct, is also located in Nankai.

Historically, northern parts of Nankai District were located inside the walled city of Tianjin.

Nankai became part of the military garrisons during the Ming and Qing Dynasties and the city wall served as a major defense system against foreign invasion in the late 19th century.

Small populations of ethnic minorities such as the Hui, Manchu and Mongol peoples also exist.