In an eye-tracking experiment, we investigated whether and how a comma influences the reading of Chinese sentences comprised of different types of syntactic constituent such as word, phrase and clause. Participants read Chinese sentences that did or did not insert a comma at the end of a syntactic constituent. The results showed that the fixation times were shorter for the target word followed by a comma than for that followed by no comma, which suggests that a comma facilitated word identification during the reading of Chinese sentences. Furthermore, the insertion of commas shortened the total fixation times in the post-target region only for the clause condition. The data are consistent with previous findings concerning the role of segmentation cues in reading, and compatible with the implicit prosody hypothesis.