Abstract: Zhongyuan urban agglomeration is an important spatial platform advancing "rise of middle of China", also the indisputable main item realizing "rise of the Zhongyuan Plains" in Henan Province. In the integrated development of Zhongyuan urban agglomeration, the construction of the urban system with perfect structure and formidable function is a special important historic task, and the structure optimization of the urban system is a key problem that should be solved properly. The essence of the structure optimization of the urban system is, through government's macroscopic plan regulation and urban agglomeration's integration, to realize the high degree of harmony of the cities with different ranks, different scales and different functions in the spatial platform, thus realizing the promotion of the urban system's overall strength, and finally realizing the sustainable development of urban agglomeration. The primary content of the structure optimization of the urban system in Zhongyuan urban agglomeration is: the rank level optimization, the scale sequence optimization, the function type optimization and the spatial layout optimization. First, the rank level optimization of the urban system. This article uses the law of "city centricity intensity" to divide the rank of all cities in Zhongyuan urban agglomeration, and then constructs four rank levels of the urban system. Second, the scale sequence optimization of the urban system. This article uses the gray system GM(1,1) model, and, according to the status, economic development situation as well as population machinery growth foundation of different cities, to extract the optimized target of the non-agricultural population of various cities in 2020. Third, the function type optimization of the urban system. This article incorporates industries into 8 departments reflecting city function activities, uses Nelson's(H.J.Nelson) statistical analysis principle and method to determine the superiority functions, the prominent functions, the function intensities and the specialization indexes of the cities in Zhongyuan urban agglomeration. Fourth, the spatial layout optimization of the urban system. Around 2020, Zhongyuan urban agglomeration will form an overall pattern of city space layout and function display: "two circles, double nucleuses, four belts and one triangle".

Key words: Zhongyuan urban agglomeration, integrated development, urban system, structure optimization