||The circumstances caused by illegal and chaotic on-street scooter and bicycle parking have induced the severe negative effect upon passing on sidewalks, environment on shopping streets, and traffic on roads in central business district. The local government has attempted to solve this problem by implementing related strategies. However, the parking problem is not be resolved sufficiently owing to many types of travel behavior including parking location choice involve social interaction effect, leading society into social dilemma. The past travel behavior models, used to be bases for policy assessments, assumed that individual behavior is independent of others and therefore it resulted in the constrained performances. In view of the above, this study takes the CBD of Tainan City as the study area, where the stated preference data aimed at parking location choice behavior are collected to build an econometric model being capable of analyzing the collective behavior in the presence of social interaction effect. Accordingly, the threshold value, provided through policy interventions, achieving equilibrium shift of collective behavior could be assessed quantitatively. Consequently, reducing distance (from parking lots to destination) 140m, declining the fixed fee (the parking fee per time) 8 NT dollar (around 0.276 US dollar), or using composed policies, to reach threshold would increase the proportion of off-street parking from the present 5.0% to 71.4%. Moreover, the implementation sequence of policies combinations with feasibility is proposed and examined. Consequently, the result provides a useful reference for the phased implementation of urban transportation plan.