The present study explored the mediating effect of word detection on the relationship between visual-spatial attention and reading comprehension in Chinese. The participants included 287 Hong Kong Chinese children (167 third graders, 84 girls, "mean age" = 8.73, SD = 0.49, and 120 fourth graders, 45 girls, "mean age" = 9.93, SD = 0.51). Using structural equation modelling, we found a significant direct effect of visual search on reading comprehension, after age, non-verbal IQ, and Chinese character reading were included in the model. The relationship between visual search and reading comprehension was also found to be mediated by Chinese character reading. When word detection was entered to the model, the relationship between visual search and reading comprehension was fully mediated by both word detection and Chinese character reading. When reading comprehension measured 1 year ago was further controlled, only the mediation of word detection turned out to be significant. The results highlight the importance of visual search in passage reading in Chinese and the mediating role of word detection in understanding this relationship.