Enhanced pitch perception has been identified in autistic individuals, but it remains understudied whether such enhancement can be observed in the lexical tone perception of language-delayed autistic children. This study examined the categorical perception of Mandarin lexical tones in 23 language-delayed autistic children and two groups of non-autistic children, with one matched on chronological age (n = 23) and the other on developmental age in language ability (n = 23). The participants were required to identify and discriminate lexical tones. A wider identification boundary width and a lower between-category discrimination accuracy were found in autistic children than their chronological-age-matched non-autistic peers, but the autistic group exhibited seemingly comparable performance to the group of developmental-age-matched non-autistic children. While both non-autistic groups displayed a typical categorical perception pattern with enhanced sensitivity to between-category tone pairs relative to within-category ones, such a categorical perception pattern was not observed in the autistic group. These findings suggest among language-delayed autistic children with a developmental age around 4, categorical perception is still developing. Finally, we found categorical perception performance correlated with language ability, indicating autistic children's language disability might be predictive of their poor categorical perception of speech sounds.