Sensory anomaly in autism is thought to arise from atypical Bayesian inference processes in the brain. It remains elusive, though, which neuronal circuits are involved. Here we focused on the superior colliculus and performed in vivo two-photon calcium imaging while the mice were engaged in an implicit visual learning task. Following the Bayesian learning principles, wild-type mice showed contextual modulation of the visual responses in the superior colliculus and pupil dynamics, but not in the retinal signals. In contrast, Scn2a-haploinsufficient autism model mice exhibited anomalous modulation patterns. Using chemogenetic tools, we selectively blocked the feedback input from the primary visual cortex to the superior colliculus, and identified that this top-down signaling mediated the observed modulations, both at the neurophysiological and behavioral levels. These results indicate that the corticotectal input is critical for contextual sensory integration in the superior colliculus, and that its impairment underlies atypical learning in autism spectrum disorder.