As China progresses in its high-quality development and new urbanization, the spatial development pattern of large cities is evolving from expansion of scale to optimization of existing stock. The polycentric system is widely utilized in guiding the macro-structure of spatial planning, playing a critical role in transforming urban development strategies, increasing urban efficiency, alleviating urban diseases and promoting urban renewal. This study establishes a framework for analyzing spatial performance in urban polycentric systems. With Hangzhou as the focal example, the evaluation proceeds across four dimensions of spatial performance, examining the city's internal spatial organization and the mechanisms of its formation. The results indicate that: (1) The polarization effect of the main center outweighs its diffusion, leading to a development pattern characterized by strong primary and secondary centers, weak tertiary centers; concentration in the old cities, dispersion in the outskirts, differentiation of tertiary centers, with distinct disparities in the effectiveness of planning guidance; (2) Centers in the urban core and principal development directions generally exhibit high performance, with spatial forms moving towards integration or central dissolution; (3) Activity density performance maintains a balanced state at lower levels, with centers in tertiary areas and primary development trajectories achieving greater equilibrium; (4) Industrial upgrading and the construction of significant facilities drive the functional differentiation of the polycentricity, displaying patterns of horizontal and vertical divisions among center functions; (5) Travel efficiency performance aligns with the polycentric configuration, incrementally revealing the balanced nature of employment distribution across centers; (6) The evolution of the center system is shaped by a confluence of historical path dependence, natural geographic characteristics, economic and industrial development, advances in social demand, and government policy directives, especially those driven by government administrative efforts including development strategies, spatial planning, resource distribution policies, and major events, all of which have a pronounced guidance effect. Future initiatives should concentrate on the cooperative division of functions within the polycentric system, adapting spaces to meet the specific needs of different industries related to spatial and transaction costs, thereby forming both comprehensive and specialized centers. Utilizing major events and infrastructure-driven mechanisms should elevate the energy levels of centers. Moreover, the needs of micro-entities should be addressed by capitalizing on the economic effects of aggregation and market mechanisms to facilitate the orderly emergence and growth of autonomously formed centers. Strategic allocation of crucial resources through government administrative capabilities and policy instruments is essential to boost the development potential of peripheral secondary and tertiary centers. © 2024 Science Press. All rights reserved.