Touchscreen devices have become the mainstream terminals for human-information interaction and have great appeal to children. Scholars still have disputes on the effects of touchscreen learning in young children aged three to six. This study aims to investigate whether touchscreen devices can promote young children's learning achievements, and to explore the mechanism triggering young children's touchscreen learning. Fifteen articles involving 5075 participants were included into the meta-analysis, in which corresponding combination of effect size and sub-group analysis were conducted. The result indicates that touchscreen learning can promote young children's learning achievements in general. Subject is a significant moderator for young children's touchscreen learning. Touchscreen devices has the best positive effect on young children's visuo-spatial ability, but little on literacy and arithmetic ability. The advantages of touchscreen learning for young children's academic performance could be maintained compared with different traditional teaching methods, and lasted throughout the whole stage aged three to six. There is a contradiction between embodied cognition theory and cognitive load theory in explaining young children's touchscreen learning. The Embodied Cognitive Load Theory and three types of learning (sensorimotor load superiority learning, processing load superiority learning, and double loads learning) were put forward as the theoretical assumption to explore the mechanism and convergence of young children's touchscreen learning.