This study examined the effect of reading fluency on the reading miscues of fourth-grade elementary school students in Taiwan. The 63 research participants with good reading fluency were selected from 210 students and reading miscue analysis and retrospective miscue analysis were used to examine them. The study results found that "substitution of meaning" in section "substitution" appeared the most in reading miscues. After retrospective interviews, it was found that students would replace words based on their reading experience, reading habits, and prior knowledge, resulting in reading miscues. It is suggested that teachers should have standards for the interpretation and mastery of text words when teaching to reduce students' different performance in word learning and avoid affecting reading comprehension and reading fluency.