Abstract: Tracing to source is the main method of moral genesis. This paper uses the tracing method to investigate the origin of the ancient Greek and Roman concept of perceptual good and evil. The first part points out that the Greeks in Homer’s time had formed a moral judgment mode with the concept of good and evil as the basic tool, and had their own perceptual view of good and evil through the trace of language and history. The poets Homer and Hesiod concretized these two moral concepts, put forward moral judgment and evaluation for many behaviors, and then put forward moral precepts, so that their works played the role of moral education. The second part points out that the birth of rational thinking has facilitated the development of Greek ethical thought through the investigation of the good and evil views of Greek philosophers in the early and classical periods. Philosophers of all ages have been rational processing of the perceptual view of good and evil of Homer and Hesiod, on the basis of which the rational view of good and evil with different theoretical forms has been developed. The third part points out that the rational view of good and evil continued to expand and inherit in the Hellenistic period and the Roman Empire period and formed the rational view of good and evil with different contents and structures.