Objective: The goal of this study is to research how mother’s literacy interaction influences children’s interest in vocabulary and reading. Methods: The research subjects selected were 120 children who were three to four-year-old and their mothers. This study conducted questionnaires about the literacy interaction of the mothers. This study also surveyed vocabulary and interest in reading of the children by directly visiting the institutes and by researching the subjects individually. This study used technical statistics, Person’s product- moment correlation analysis, and multiple regression analysis in order to analyze the collected data. Results: The results of this study are summarized and concluded as follows. First, open interaction among the sub-areas of a mother's literacy interaction significantly affected children's vocabulary. Second, a mother's literacy interaction with children had no direct impact on the child's interest in reading. Conclusion/Implications: The mother’s literacy interaction could have a correlation with the vocabulary development of three to four-year-old children, and a mother's application of open interaction could significantly influence the receptive vocabulary and expressive vocabulary of children.