Autistic children (AC) show less audiovisual speech integration in the McGurk task, which correlates with their reduced mouth-looking time. The present study examined whether AC's less audiovisual speech integration in the McGurk task could be increased by increasing their mouth-looking time. We recruited 4- to 8-year-old AC and nonautistic children (NAC). In two experiments, we manipulated children's mouth-looking time, measured their audiovisual speech integration by employing the McGurk effect paradigm, and tracked their eye movements. In Experiment 1, we blurred the eyes in McGurk stimuli and compared children's performances in blurred-eyes and clear-eyes conditions. In Experiment 2, we cued children's attention to either the mouth or eyes of McGurk stimuli or asked them to view the McGurk stimuli freely. We found that both blurring the speaker's eyes and cuing to the speaker's mouth increased mouth-looking time and increased audiovisual speech integration in the McGurk task in AC. In addition, we found that blurring the speaker's eyes and cuing to the speaker's mouth also increased mouth-looking time in NAC, but neither blurring the speaker's eyes nor cuing to the speaker's mouth increased their audiovisual speech integration in the McGurk task. Our findings suggest that audiovisual speech integration in the McGurk task in AC could be increased by increasing their attention to the mouth. Our findings contribute to a deeper understanding of relations between face attention and audiovisual speech integration, and provide insights for the development of professional supports to increase audiovisual speech integration in AC.