This study has been performed by collection of questionnaire and statistical analysis. The students at 6th Grade of Elementary Schools in Kaohsiung City are taken as the basis. It has randomly chosen 650 students as the target of study. The data collected from the investigation, is examined by independent sample t-test, one-way ANOVA, Pearson Product-Moment Correlation. This conclusion are as follows: 1. Parental Attitudes toward domestic sex Education: Paraents have a good attitude toward domestic sex education. With different gender of children, parent-child communication and the atmosphere of family discipline, their sex attitude toward domestic sex education are obviously different. 2. Children's sex knowledge: Children have a mid to high level of sex knowledge, "the awareness of sexual harassment and sexual assault" is at the highest scores. With different educational attainment of parents, family type, parent-child communication, and the atmosphere of family discipline, their sex knowledge are obviously different. 3. If the consciousness of parental attitudes toward domestic sex education is higher, childr en'sex knowledge will be higher.