The concept of Smart City (SC) with its ambitious scheme has successfully attracted the interests of different stakeholders (i.e., government, information and communication technologies vendors, as well as researchers). While great efforts have been concentrating on the interpretation and the implementation of the ‘smartness’, the incentives for SC development are ignored. Understanding the incentives would clarify the goals of SC development and thereby boost its development efficiency. By exploring existing researches and cases of Nanjing, China, 15 factors were identified using a proposed physical-human society-cyber (P-H-C) space model. A structured questionnaire survey was conducted among different stakeholders in Nanjing to investigate their attitudes towards these factors. In factor analysis, these factors are grouped into three dimensions: technology push, government pull, and user-driven. Results show that currently SC development is mainly pushed by the technical progress and innovations. Meanwhile, government plays a significant role in pulling SC development especially at the initial stage. In addition, requirements to enhance the experience of end-users including government, companies, citizens etc. are critical for SC development. This paper provides insight on the incentives of SC development, research findings could be used as guidelines for the SC development in cities worldwide.