Prior researches on customer's complaining behavior seem to focus on how service failures directly leads to external behavior of customers, while ignoring psychological perceptions of customer about service failure. This study researches a psychological mechanism of the customer's complaining behavior from the perspective of self-concepts. Taking travel agency tourists as subjects, the study uses controlled simulation experiment to test the influence of customer's self-threat perception on complaining motivations in different contexts of service failure, and to investigate the moderating effect of customer's self-monitoring as well. Results indicate that service delivery system failure has a positive impact on customer's public self-threat perception, demand response failure positively affects customer's public self-threat perception and private self-threat perception in the same time; employee's spontaneous redundant behavior mistake only has a positive effect on customer private self-threat perception;self-threats perception has a mediating effect between service failure and customer's complaining motivations; self-monitoring has a negative moderating effect on the relationship between self-threats perception and complaining motivations. The conclusions are of great significance for service enterprises to focus on customer's self-concept restoration to copy with the customer's complaints.