Seventy-eight percent of the total global carbon dioxide emissions come from urban areas, which consume 70% of global energy. Land-use and cover changes contributes one-third of the urban carbon emissions. Thus, understanding the mechanism of urban carbon metabolism through simulating process of biological metabolism could help to control carbon emissions in urban areas; this is the key to mitigating the crisis of global warming. As part of the goal of reducing carbon emissions, the goal of this study was to understand how land use changes during urbanization influenced carbon metabolism. This study used Hangzhou as an example, and developed a spatially explicit model of carbon transfer between components of an urban system, and then used the ecological network utility analysis to explore the structure and function of the network, and determine effects of ecological relationships among components that resulted from carbon flows, their spatial distribution, and their changes over four time periods (1995-2000, 2000-2005, 2005-2010, 2010-2015), and finally used the mutualism index (M) to judge whether land use changes had positive effects on urban carbon metabolism. The results showed that:(1) Based on the empirical coefficient model, the carbon metabolism was determined; the net carbon flow continued to have negative effects during the study period and reached a peak in the period of 2000-2005, which indicated a serious imbalance in the urban carbon metabolism. The negative carbon flow mainly came from the transition between cultivated land and industrial land, and the positive carbon flow was mainly from the transition between industrial land and urban land; (2) During the period 1995-2015, the mutualism index (M), which indicated synergistic effects among components in the urban carbon metabolism, increased at first, then exhibited a downward trend, and finally began to grow again. In addition, the average value of M was less than 1, indicating that the comprehensive effect of land use change on the urban carbon metabolism was negative; (3) Competitive and mutualistic relationships were distributed differently among components of the urban carbon metabolism:the competitive relationships accumulated in negative metabolism components with high carbon emission density, such as industrial land and highway and railway, whereas the mutualistic relationships accumulated in positive metabolism components of high carbon sequestration density, such as forest land; (4) Based on the ecological network utility analysis, the study indicated that the change in the spatial distribution of ecological relationships resulted from carbon flow between components of urban carbon metabolism. For 1995-2000 and 2010-2015 (at intervals of five years), the trends of the three ecological relationships were as follows:the exploitation relationship exhibited changes spreading northwest, southwest, and south, moving towards to the northwest and the southeast; the competitive relationship exhibited trends moving towards the southeast and spreading to the south and northwest in a scattered distribution. The mutualistic relationship exhibited a trend moving to the southeast with a non-scattered distribution. Our research results provide a theoretical basis to plan adjustments to the city's land use structure to achieve the goal of a low carbon city.