During the COVID-19 pandemic, video materials have played crucial roles in supporting learning among children with autism spectrum disorder (ASD). This study aimed to explore the effects of the instructor's facial expressions in video lectures on attention and motor learning in children with ASD versus typically developing (TD) children. A total of 60 children were randomly assigned to four groups: (1) ASD-happy, (2) ASD-neutral, (3) TD-happy, and (4) TD-neutral. Both happy groups paid more attention to the video lectures. The ASD groups achieved higher accuracy and fidelity of motor learning when the instructor smiled. Results revealed that greater attention to video lectures predicted better performance in children with ASD. This study has practical implications for the design of learning materials for children with ASD: An instructor should be encouraged to show a happy expression to promote learning.