Ethics is the key factor for the enterprises to achieve sustainable development. However, the phenomenon of individual unethical behavior occurs frequently in the organization. Therefore, it is very important to motivate employees’ moral consciousness and to induce their ethical behavior. In this paper, we discuss the negative effect of self-leadership on unethical behavior. We collected 330 paired sample data and the results showed that accountability partially mediated the relationship between self-leadership and unethical behavior. Law and code climate moderated the relationship between accountability and unethical behavior. When law and code climate is high, the effect of accountability on unethical behaviors is stronger. The results of this study are conducive to the in-depth understanding of the inner mechanism of employees, and provide an effective way to regulate and manage employees’ ethical behavior from the perspective of intrinsic motivation.