he purpose of this study was to identify differences in the development of children aged 0~42 months during the COVID-19 period focusing on their gender and whether their parents had completed parental education program. Survey data from 146 children aged 0 to 42 months in S city using K-Bayley-Ⅲ were taken for analysis, using Crossover Analysis, Accuracy verification, Bonferni verification. The study revealed the following results. First, Significant differences were found in language, motor, and adaptive behavior areas. It was confirmed that there were significantly more cases of boys showing language development at the sub-average borderline level compared to girls. It was confirmed that there were significantly more cases of boys showing below-average motor development than girls. In the area of adaptive behavior, it was confirmed that the ratio of girls at the average level and boys at the excellent level was significantly higher. Second, It was confirmed that when the primary caregiver did not receive parental education, the rate of children showing a below-average level of development was significantly high. This suggests the need to systematically prepare and actively introduce parenatal education programs and the development of exercise programs that parents and children can participate in together, so that parents can understand the differences in development according to their children's gender and make appropriate interventions at home.