Answer :
It is called one contry two systems. It underlines the fact that Hong Kong is part of China: so it's one country, but it has two systems (for now): Mainland China is communist and Hong Kong capitalist.
The relationship between China and Hong Kong is sometimes called ONE COUNTRY, TWO SYSTEMS.
According to this doctrine, although it is recognized that China is a single country, under the regime of the People's Republic of China, it is accepted that within that unified Chinese State there coexist different economic and political systems in certain areas, including maintaining capitalism in certain regions of the country, like Hong Kong or Macau, in parallel with the socialist system.
