The threat of self-interest as an environmental factor can affect the ethical decision-making process of auditors. Therefore, the purpose of this study is to investigate the effect of the threat of self- interest on ethical sensitivity, with an emphasis on the role of mediator of the ethical severity of auditors. This research is a quasi experimental study and the statistical population of the study includes auditors working in private audit firms in 2018, of which 186 were selected as sample volumes. The research data were collected through a questionnaire and analyzed using the structural equation modeling using PLS software. Findings show that the threat of self- interest has a positive and significant effect on ethical sensitivity, and this effect is exacerbated by the variable of moral intensity. Therefore, based on the theory of social cognition, it can be argued that the existence of a Self-Interest  Threat due to fears that poses the negative consequences of these threats to auditors can increase the ethical sensitivity and moral intensity of auditors to ethical issues.