The construction of smart cities is an important trend in the current urban governance practice. Based on the smart city policy roadmap and policy model framework proposed by the G20 Global Smart Cities Alliance，this paper introduces the open data to combat crime in Mexico City，and the ICT accessibility practices in Istanbul，Turkey，and summarizes the policy objectives，implementation plans and policy implications of smart city construction. For China，the construction of smart cities needs to establish a demand-centered smart city construction strategy，strengthen the inclusiveness and inclusiveness of smart city construction，and pay attention to the construction of long-term mechanisms for smart city construction.