Abstract: We define condition that athletes are distracted by some unrelated thoughts in competition as mind- wandering. It is a pervasive phenomenon that individual become decreasing awareness of task and external environments. Theories and empirical researches about choking and mind-wandering have been analyzed and reviewed. Existing results indicated that mind-wandering under pressure might be one of the causes of choking. Mind-wandering was more likely happened when athletes focusing on results/rewards of competition. Task characteristics play a role of moderator between mind-wandering and competition performance. We could predict distractions and worries of athletes in competition by measuring their rates and contents of mind-wandering among daily life, training and cognition task. Mindfulness training could enhance competitors' performance through decreasing mind- wandering. Thus, theories of mind- wandering have made clear how task- unrelated thoughts lead to under-performance compared with choking theories.Methodsof measuring and intervening are operable, and has a number of applications.