Taking Beijing and Lanzhou as cases， through comparative analysis， this paper studies the characteristics of centralized and decentralized urban structure and space design， and evaluates the performance in four aspects: land use， green space system， road system and livable index. It is found that centralized cities have advantages in land use and urban livable index， while decentralized cities have comparative advantages in green space system and road system. This paper further explains that the centralized and decentralized cities should combine their own characteristics to improve and optimize the strategy in the specific design process.