In the ethical environment of family poverty, Tess's original complete family ethical structure was destroyed. In the state of extreme poverty, it is difficult to obtain correct ethical concepts and construct their own ethical norms. At the same time, because the human factors of D 'Urberville, Clare and others are restricted by animal factors, their ethical consciousness cannot be generated and their rationality cannot be mature, which leads to their identity dislocation in the process of determining their ethical identity, which eventually leads to ethical confusion. Therefore, the occurrence of tragedy has become inevitable.