With the couple of paradoxical tendencies transfotruing urban space, concentration and de-centralization, the paper aims at establishing a philcf, ophical perspective, interpreting the complexity of evolution of urban spatial structure. It firstly reviews the twin concepts in various disciplines. Thisil lustrates their heuristic power as philosophical particles. Their connotation in sphere of urban spaceev olutiOn is further scrutinized as two basic resultant forces, of the sophisticated mechanisms beyond urban sDatial evolution. The mutuality of concentration and decentralization as two aspects of unityoi oppdsites is a fundamental contradiction of urban spatial evolution. It is argued that the spatial meaning of concentration and decentralization in the philosophic method, and paradoxical recurrent trends of concentration and decentralization are abstracted as a pervasive intrinsic feature of urban spatial evolution. I ased On this, Secondly, the paper proceeds to survey theoretical explanations urban spatial evolution. with the controversial performance Of concentration an d decentralization as the monotype, and Dut forard that the urban spatial evolution is under the contradictory development of co ncentra-tion and decentralization. Although urban spatial evolution exhibits colorful patterns of concentration and decentralization, it is still po ssible to conclude in some common laws. Therefore the paper investl-gates into the cutrent trends, revealing the concentration dialectic in evolution of urban space After discussed academic view of co ncentration an d decentralization an d the track of city development, then Dointed out mechanism characteristics an d unified trend of concentration and decentralization. Finally, the paper cOntends that because of the difference of socio-economic backdrops, the play of concentra-tion and decentralization of urban space exhibits distinguished features. The pape r emphasize this will be convenience of understand and hold the evolvement regulation of urba n space, an d guide oty devel-Dment fulfillment in our country. This paper cover six parts: (1) discussed academic view of the con cedt of concentration and decentralization in the philosophic method, (2) the spatial meaning of con-centration and decentralization, (3) the controvert of concentration and decentralization in academ cresearch, (4) the cncentration dialectic in evolution of urban space. (5) the philosophic deduction of ncentration and decentralization (6) the conclusions.