Fluent reading, which involves visual serial processing of letters/characters (i.e., visual temporal processing, VTP), greatly contributes to our daily life. The present study thus explored the underlying mechanism of reading fluency from the perspective of VTP. A longitudinal method was adopted to examine whether VTP skills in preschool (mean age of 5.03 ± 0.06 years) could predict reading fluency after 2 years (mean age of 7.10 ± 0.18 years). Low- and high-level VTP skills were systematically measured. The results showed that VTP skills at both levels could significantly predict later development of reading fluency. Moreover, the relationship between low-level VTP skills and character reading fluency was mediated by high-level VTP skills, suggesting a possible mechanism underlying the relationship between VTP and reading fluency in Chinese. The possible role of VTP in fluent reading, which would have implications for the early diagnosis and remediation of reading disability, has been further discussed.