This study investigates speech rate development of Korean-speaking young children in a relation to VOT distinction. Speech rate is a duration-based acoustic measure and crucial parameter to determine language development and language processing. To examine children’s speech rate, a production experiment was conducted with three- and four-year-old Korean-speaking children. The two child groups showed insignificant speech rate differences in mono- and bi-syllabic words, while the difference from adult speakers apparently increased in bi-syllabic words. Even though children showed adult-like VOT distinction patterns across three stop categories, the ratio of VOT to word duration was different from that of adult speech. This finding indicates that adult-like VOT distinction development in a segment level would emerge ahead of adult-like speech rate development. The results suggest that children in those ages did not show adult-like speech rate control, and for the speech rate control development, multiple linguistic features and cognitive factors are related. The 3- or 4-year-olds need to further develop speech rate.