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*.