The characters literally combine to mean “love (and) hate (are) divided clearly.” The phrase paints a vivid picture of a person whose emotional and moral landscape has a sharp, clear line drawn between what they cherish and what they despise.
In Chinese culture, being 爱憎分明 is often seen as a virtue, especially when describing heroes, righteous officials, or people of great integrity. Traditional stories and operas are filled with such characters who stand firmly for justice and against evil, with no room for ambiguity. This reflects a cultural value for moral clarity and loyalty.
This idiom is still very much in use today, both in formal and informal contexts.