Intercity relationships play a crucial role in cities’ development, with the coexistence of cooperation and competition between twin-cities being particularly distinctive. This study uses panel-data of 8 pairs of twin-cities and 14 pairs of control group cities in China to empirically analyze that, it reveals that twin-cities’ sharing of development resources through cooperation, and the stimulation of internal motivation through competition, both of those significantly enhance the economic performance of them. The combination of “strong-strong” and “short distance” partnerships of twin-cities leads to better developmental effects of cooperation and competition. The special partnerships of twin-cities also contain general laws of intercity cooperation and competition, revealing spatial characteristics of intercity game like “cooperate with the distant cities and compete with the nearby ones”. In the new phase, it should coordinate the relationships between twin-cities to fully release their distinctive development momentum, gradually optimize the spatial economic structure in single-core provinces, and promote positive intercity competition and cooperation among cities.