Positioned within rapport management theory proposed by Spencer-Oatey, this article investigates the customer service agent’s pragmatic identity construction in complaint response calls. Drawing on data of 42 complaint handling recordings from the customer care center of a Chinese airline company, this study tries to address these three research questions: 1) What types of pragmatic identities do the customer service agents construct in complaint response calls? 2) How are these pragmatic identities constructed through rapport management strategies? 3) What interpersonal functions do these pragmatic identities perform? By adopting a qualitative research method, this study has found that the agents mainly construct three default identities and one deviational identity in complaint response calls by employing nine rapport management strategies from four rapport management domains. These different pragmatic identities mainly perform three kinds of interpersonal functions: support face needs, support sociality rights and obligations, and support interactional goals. The findings further validates the feasibility of rapport management theory in the study of identity construction, and provides new ideas for future study on pragmatic identity construction in institutional communications.