Pedestrianization is at present a definition and topic attracting great attention, while the theory and practice it belongs to is diverse. This paper tries to clarify the process and characteristics of development of pedestrianization, and provide clearer references for development of pedestrianization and pedestrian environment in urban area. It mainly adopts the method of time-spatial (T-S) comparative analysis. In T-dimension, the process of development of pedestrianization in different period is checked. And in S-dimension, it chooses pedestrianization in German and US as samples to compare differences of performance and mechanism of pedestrianization in different areas. It’s found that development of pedestrianization has experienced two transformations in history, both taking place in characters of property and spatial, consisting of two binary relationship of exclusive-public and indoor-outdoor. Meanwhile, in comparison analysis, transformation in property is more important than in spatial. Pedestrianization, as a definition with long history, has new connotation and function in motorized period. Meantime, pedestrianization is a comprehensive definition covering aspects of economy, transportation and society, not simply a strategy for urban development.