The issue of epistemology and practical rules of “how to construct news facts” cannot ignore the ontological problem of “based on what kind of real construction of news facts”. Therefore, the study of objectivity in journalism should also go deep into the ontological structure of the news facts world. Based on the thought of critical realism, this study outlines the triple structure—the reality category, the spatial category and the diachronic category—of the news facts ontologically. Objectivity in journalism, as a unique epistemology and practical rule in the field of journalistic knowledge production, is closely related to the ontological structure of news facts.