In Chinese reading, the possibility and mechanism of semantic parafoveal processing has been debated for a long time. To advance the topic, "semantic preview benefit" in Chinese reading was reexamined, with a specific focus on how it is affected by the semantic relatedness between preview and target words at the two-character word level. Eighty critical two-character words were selected as target words. Reading tasks with gaze-contingent boundary paradigms were used to study whether different semantic-relatedness preview conditions influenced parafoveal processing. The data showed that synonyms (the most closely related preview) produced significant preview benefit compared with the semantic-related (non-synonyms) condition, even when plausibility was controlled. This result indicates that the larger extent of semantic preview benefit is mainly caused by the larger semantic relatedness between preview and target words. Moreover, plausibility is not the only cause of semantic preview benefit in Chinese reading. These findings improve the current understanding of the mechanism of parafoveal processing in Chinese reading and the implications on modeling eye movement control are discussed.