This study was about the effects of rhythm regularity-based music intervention on reading fluency in children with developmental disabilities. The purpose of this study was to develop and apply music intervention based on regularity of rhythm repetition, predictability, consistency, etc. for children with developmental disabilities in the 2nd to 5th grade of elementary school who are attending B city and are a key period for reading ability development. The experimental group was randomly assigned to 8 people and the control group was randomly assigned to 7 people. The experimental group was provided with rhythmic regularity-based music intervention once a week for 50 minutes for a total of 6 sessions, and the control group was provided with a reading program at the same time. To measure reading fluency, the BASA-R scale test was conducted and the results of the study are as follows. First, as a result of verifying the difference in BASA-R pre-post test scores between groups, there was no statistically significant difference in BASA-R sub-area accuracy, but there was a significant difference in BASA-R sub-area speed. Second, the experimental group showed a statistically significant difference in the accuracy and speed of the rhythm sub-area between the pre- and post-test scores of 10 patterns of rhythm between the groups. This study can be applied as a basic data for the research and development of music intervention programs for improving reading related to children with developmental disabilities by examining the effects of rhythm regularity-based music intervention on reading fluency of children with developmental disabilities.