According to BBC Source The US airline will buy $200m (£159m) worth of shares in the Chinese firm and the two will “seek to increase cooperation”.
China Southern is the latest of China’s top airlines to bring in an investor from outside the mainland.
The deal should offer American Airlines more possibilities to tap into China’s growing aviation market.
In a filing to the Hong Kong stock exchange, China Southern said the two sides would work together to share transport, staff and airport facilities – as well as cooperating on code sharing and passenger loyalty programmes.
China Southern is the last of China’s three major airlines to bring in a strategic investor from outside mainland China. Hong Kong’s Cathay Pacific holds about 18% in flag carrier Air China while US airline Delta bought a 3.6% stake in China Eastern in 2015.
American Airlines will own a 2.7% share of its new partner.
Chinese carriers have been aggressively expanding their fleets and boosting international destinations to cater to the strong growth in outbound Chinese travel. China is one of the biggest sources of tourists to the US.