Research on the distribution of parts of speech has found that the proportion of nouns in different languages is relatively stable at approximately 37%. This has been verified by a large amount of language data, but currently, there is a lack of explanation for this phenomenon. Starting from ontological philosophical thought, this study proposes a cognitive description framework for the world. Based on the descriptive framework with parameters, the distribution proportion of verbs in the text was 18.5% and the ratio of the proportion of nouns to that of verbs was close to 2:1. Experiments based on corpora verified that there should be a theoretical value for the proportion of nouns and verbs, which showed that the cognitive description framework proposed in this paper can explain the phenomenon of constant distribution of nouns and verbs to some extent. In addition, we found that the distribution of nouns and verbs was affected by text-genre factors. The ratio of the proportion of nouns to that of verbs can be used to distinguish between information-based and imaginative genres in Chinese and English.