Backpacking has become increasingly popular as an ecotourism activity in China in recent years. To promote sustainable development of tourist sites and to direct and regulate environmentally responsible behaviors, travelers must behave responsibly. This study used the “attribution theory” and “norm-activation model” to create a theoretical relationship model between personal norms, group identification, and the willingness of backpackers to act responsibly to investigate the factors that influence their willingness to behave in an eco-friendly manner. The study empirically tested the model using data from a sample of 309 backpacking tourists. The study investigates the internal and external mechanisms influencing the environmentally friendly behavior of backpackers. The findings show that (1) Backpackers' “personal norms” significantly increased their willingness to behave in an environmentally friendly manner. (2) These “personal norms” are influenced by two cognitive factors: tourists' “awareness of consequences” and “attribution of responsibility”. (3) The “group identity” plays a positive moderating role in the influence of “ascription of responsibility” on “personal norms”, while it plays a negative moderating role in the influence of “awareness of consequences” on “personal norms”. (4) Meanwhile, this study explores and compared tourists, an exceptional group of tourists, and concludes that, within an environmentally conscious tourist group, group identity plays a significant role in forcing tourists to take high-quality environmental protection actions. The findings of this study investigated the norm-activation model at the group level, enhanced the micro cases and theoretical knowledge of the model to examine the willingness of backpackers to engage in environmentally responsible behaviors, and offered some practical insights on managing destination tourists.