Abstract: The tourism effect of urban Marathon is a multi-level and multi-field transitive change produced by the interactive development of Marathon events and urban tourism environment, including economic, social and spatial effects. Adopting a semi-quantitative method combining "relationship test" and "perception measurement", the impact of Chinese Marathon events on urban tourism is evaluated by selecting the four international Marathons of Beijing, Shanghai, Xiamen and Dalian as analysis objects. The results show that the comprehensive effect evaluation value of urban Marathon tourism is A_i=4.12, which is in the upper middle level; urban social effect(A_i=4.15)> economic effect(A_i=4.11)> spatial effect(A_i=4.09). It is proposed that the Marathon race, as a catalyst for urban development, carries the hope of modern urban evolution and selfrenewal, and is related to more ambitious government public policies because it affects the variation of urban competitive status in the post-industrial era; the impact and depth of Marathon events in the development of urban tourism depend on local governments'values and systems arrangements and innovative measures; critical factors to enhance the tourism effect of urban Marathon in China include:to innovate the production and service model of urban Marathon events, to create a benign mechanism for the sustainable development of event tourism, and to make Marathon events a core tourism event for sustainable urban development.