The focus of this research is on the distribution and movement of population and the characteristics of travel demand in the Taipei, metropolitan area. It demonstrates that the diffusion of population through suburbanisation has alleviated population concentration in the city, and the transportation network should be improved, if possible, in accordance with the increasing needs of travel demand. The differences of population distribution between daytime and nighttime among regions reflect .the scattered activities and the intensity of traffic flo which shows the traffic volume generated and attracted mutually among the regions. The study finds the imbalance in the movement of population. among regions and the strong movement of population between daytime and nighttime. The pressure that results from population movement on time and space causes the problems of housing and congestion. After a preliminary analysis, it is found that the imbalance of transportation supply and demand will be worse if no action is taken. Therefore, the improvement of mass transit system on which most population depend should be expedited,. especially, the existing problems such as the uneconomie radial routing of bus system should be solved. In sum, in the process of urbanization and suburbanization, the distribution of population will change in the metropolitan area, so does the travel demand pattern. For adapting to those changes, a comprehensive planning, including urban and transportation planning, should be carefully considered.