The range and complexity of interdependencies between water and carbon emissions, including synergies and trade-offs, are greatest in cities. Therefore, the investigation of urban water-carbon nexus is becoming vital for the urban sustainable development. Input-Output (IO) model is an effective tool to evaluate the direct and indirect environmental effects. However, the accurate quantification on urban water-carbon nexus is seriously constrained by the highly-aggregated sector classification in urban IO models, hindering the implement of specific urban policies. Thus, this study developed a Water Carbon-IO-Life Cycle Assessment (WC-IO-LCA) model based on a modified IO approach that disaggregates the construction sector into 12 subsectors according to different building types in cities. It aims to analyze and identify the key nodes and routes of urban water-carbon nexus in Beijing's economic system in 2010. Our results demonstrate that Electricity sector is the direct water-carbon nexus node and Construction sector is the high-intensive embodied water-carbon nexus node in Beijing. Of which, nearly 64% of embodied water and 83% of embodied carbon are derived from the source sectors in the upstream of the production supply chains for Construction sector. The culture sports and entertainment buildings presented the largest embodied water-carbon intensity, which is identified as the major control point in Construction sector. (C) 2019 Elsevier Ltd. All rights reserved.