Abstract: Most of the previous travel behavior models implicitly stipulated a biased assumption that individual decision-making is independent from others′ behaviors.Thus, these models cannot accurately reflect macro traffic situations when analyzing traffic behaviors with obvious social interaction effects.In this study,''travel mode choice behavior''is regarded as a collective behavior, and equilibrium shift states of travel choice behaviors are analyzed with a consideration of social interaction effects.Accordingly, a threshold model of travel mode choice behavior is developed.Taking parking fee as an indicating variable of policy interventions, it quantitatively estimates the threshold of eliminating inferiority equilibrium (i.e.unrestrained travel of private cars).The results show that when parking fee increases to over RMB 15 yuan per trip, the collective behavior will reach the equilibrium shift threshold, which can promote the proportion of travels using public transport from 19.3% to 72.3%.