During the COVID-19 pandemic, social distance regulations call for non-contact services, making self-service technologies gain much more attention. However, customers found they are pushed into more digital shadow work by using self-service technologies. This research aims to explore the user’s psychological mechanism, examine how shadow work influences user emotion during using self-service technologies; and further discuss how user emotion makes contributions to user behavior. Three rounds of follow-up interviews, with seven participants, and one focus group, consisting of four participants, are conducted over two months. Grounded theory is used in open coding, axial coding, and selective coding stage, and is conducted to develop the user’s psychological mechanisms of digital shadow work. We find and name 128 codes, group them into 18 categories, and finally get 7 concepts after coding. Shadow work has a complex impact on users’ psychological mechanisms. Negative emotions, such as anger, anxiety, annoyance, and worry, attribute to the perception of shadow work; and indirectly influence the user’s continuous behavior, such as stopping to use, continuing to use, and seeking alternatives. Examining users’ psychological mechanism contributes to developing the theory of shadow work academically, and also advance the development of self-service technologies practically.