Urban planning has always pursued ideal space. Building an exercisable concept is an option for current urban planning. An ideal space has two accessible approaches: an ideal spatial mode applicable to the whole human society, and another mode focusing on the ideal spatial mode which relies on a particular region. “Regional ideal space” can be defined as an imaginary spatial mode recognized by clusters of people during a certain period. With its substantive characteristics of dynamism, diversification and overplanning, ideal space is a directional impetus to promote urban evolution. Based on our research, we find that the ideal space mode of the city of Wuhan, P. R. China, has evolved from sandbank to park to unitary city. It is very important to study an ideal space of a city from the perspective of historical evolution of urban form. Studies of this type can promote the evolution of urban form, guide city change, and help people seek the ultimate goal of urban planning, both theoretically and practically.