This paper compares the allocation tendency of sentential stresses within base phrases among four reading styles, Lyric, Critical, Explanatory and Neutral. Indicators for stress tendency are defined respectively for words and within phrases to illustrate (1) the possibility for a class of words to obtain sentential stresses on sentence level and (2) which components in a base phrase is easier to obtain stresses. The final conclusions are (1) rhythmic stresses tend to locate on the final words within base phrases, regardless of reading styles; (2) allocation of semantic stresses is affected by the reading styles. The Explanatory style shares a similar allocation tendency with the Neutral style. The Critical style differs from the Neutral style mainly in phrases with the adverbial+head structure. The Lyric style differs from the other styles in many aspects because, when reading essays in Lyric style, the speaker tends to form a kind of poetry-like rhythm to get a better expression of the beauty of the essay.