In regard to the research of Informatization and Information Technology Application，an early Chinese informatization inaugurator has raised three classical questions “What，Why and How” and pointed out the reality that we barely knew anything about them，and an expert expressed that what we had mastered about the information technology application is merely a tip of an iceberg. Nowadays，as the most cutting-edge part of information technology，construction practice of smart city is flowering. However，the theoretical research of smart city is still unitary and undeveloped，practical guidance calls for more knowledge of it. The research of “What，Why，and How” about smart city is still at the primary stage. Therefore，based on the current construction and research，this research tries to rethink and explore its concept，intension and development direction of smart city. Moreover，according to the pattern “What，Why，and How”，this research also proposes a theoretical model of new smart city and explains its concept characteristics，structure characteristics and operating characteristics. Besides，the conceptual framework of new smart city will be illustrated by the case of Beijing city informatization and the forecast about Beijing new smart city construction will be done according to this framework. Finally，future research direction of Beijing new smart city construction will also be put forward.