With the explosive growth in time spent on YouTube by babies and toddlers, it's important to analyze what they're watching on YouTube. Indexes that evaluate the contents of YouTube channels for infants and toddlers have been developed, but since those were evaluation-based indexes of educators and parents, it is difficult to find out what content children are watching. In this study, the YouTube content that infants mainly watch was content analyzed in three developmental areas: cognition, emotion, and socialization. Specifically, language destruction was analyzed for the cognitive field, verbal and physical violence for the emotional field, and emotional expression, understanding others' emotions, emotional control, antisocial and prosocial behavior representation, and prosocial expression were analyzed for the socialization. As a result, the emotional index was the highest, and the physical violence index was very low. In general, emotional expression, understanding of others' emotions, and prosocial behavior, which had a positive effect on early childhood development, were higher than linguistic destruction, verbal violence, and physical violence, which had a negative effect.