When describing a restaurant, you use an adjective.  Thus, the adjective *Chinese* describes the nature of the restaurant.  Similarly *Indian Restaurant*, *Thai Restaurant* etc.

*China* in this usage is a noun and so is not appropriate in this type of phrase.  
(Although another meaning of *China* is an adjective describing something made of ceramic)

There is an alternative description for restaurants that uses a noun phrase rather than an adjective.  This is when a specific food is served, rather than a style of food.  Examples are *Burger Restaurant* or *Pizza Restaurant*.