This study investigated the context effect during Chinese sentence reading. Naming task was used via rapid serial visual representation with reaction time as index. Context effect comes from two sources: the lexical semantic priming and the sentential thematic priming which were investigated separately here. The results indicated that (1) The lexical semantic priming was found from all the subjects under the two conditions; (2) there was thematic priming in high-span readers except under the interference condition, but never in low-span readers. It supports the theory of Working Memory Capacity Constraint that the cognitive processes depending on abundance resources are constrained by working memory capacity