Objective: To analyze the relationship between self-esteem, social competence, and academic ability in early childhood and to verify the mediating effect of learning readiness on the effect of self-esteem and social competence in early childhood on academic ability in elementary school. Methods: The structural equation model was applied and analyzed based on the data of 830 students in the 7th (2014) and 8th years (2015) of the 1st grade of elementary school. The data came from the Child Care Policy Research Institute. First, skewness and kurtosis were identified through descriptive statistical analysis. Second, through correlational analysis, the correlation coefficients between children’s self-esteem, social competence, school readiness, and academic ability in elementary school were calculated. Third, after checking the reliability of each scale, Cronbach’s alpha coefficients were calculated. Fourth, confirmatory factor analysis was performed to verify the validity of each factor and the suitability of the research model, and bootstrapping was used to verify the mediation effect. Results: First, self-esteem, social competence, school readiness, and academic ability were found to have a positive correlation among the variables. Self-esteem had a positive effect on social competence, learning readiness, and academic ability; social competence had a positive correlation with school readiness; and academic ability and school readiness had positive correlation with academic ability. Second, the results of the structural model analysis showed that self-esteem and social competence not only directly affected academic ability but also had a major mediating effect in the path from self-esteem and social competence to academic ability through school readiness. Conclusions: This study has implications for elementary school preparation through cooperation and the path of elementary schools through cooperation and families.