China shares international borders with 14 sovereign states. In addition, there is a 30-kilometre (19 mi) border with the special administrative region of Hong Kong, which was a British dependency before 1997, and a 3-kilometre (1.9 mi) border with Macau, a Portuguese territory until 1999.

China has the longest land border with Mongolia - 4,677km (2,906mi).

With a land border of 22,117 kilometers (13,743 mi) in total, China also has the longest land border of any country.

More Info: en.wikipedia.org