Preliminary Discussion about Smart City

City informationalization has passed through digital city stage and informational city stage,and now moves towards smart city.In this paper,the evolution from digital city to informational city and to smart city was discussed.Smart city was the high level of city informationalization.Then,what was smart city was discussed,the related conceptions of smart city were introduced,such as Intelligent Building,Intelligent Transportation Systems and U-city in South Korea,the characteristics of smart city were analyzed,such as perceiving,response automatically,service actively,decision support and so on.At last,the development strategies about how to build smart city were presented from three aspects,infrastructure construction,application innovation and industrial development,just like building smart infrastructure,innovative applications of smart city,developing related industry of smart city.