Objective To develop the knowledge,attitude,and practice evaluation scale for teachers' early childhood sex education and analyze the reliability and validity of the scale,providing evaluation tools for the research on teachers' early childhood sex education. Methods On the basis of relevant guidelines,publications,and the theory of knowledge,attitude,and practice,a preliminary pool of items for the scale was formed by group discussions.The scale was drafted after two rounds of Delphi expert consultation.In May 2023,stratified cluster sampling was conducted,and 535 preschool teachers from Changshou District,Chongqing were selected for a survey.Cronbach's α coefficient,split-half reliability,exploratory factor analysis,and content validity were adopted to assess the reliability and validity of the scale. Results An evaluation scale for teachers' early childhood sex education was formulated,involving 27 items in 3 dimensions of knowledge,attitude,and practice.The total Cronbach's α coefficient of the scale was 0.875,and that of the knowledge,attitude,and practice dimensions were 0.902,0.743,and 0.879,respectively.The total split-half reliability of the scale was 0.937,and that of the knowledge,attitude,and practice dimensions were 0.934,0.821,and 0.912,respectively.The content validity of the scale was good,with a factor loading range of 0.500-0.836 and a cumulative variance contribution rate of 61.57.The average score of teachers' knowledge,attitude,and practice in sex education was 72.85±7.13,with a good rate of 70.84%. Conclusions The developed scale for evaluating teacher's early childhood sex education demonstrates good reliability and validity,and it can be used to evaluate the teachers' knowledge,attitude,and practice in early childhood sex education.The evaluation results indicate that teachers have low levels of knowledge,attitude,and practice in sex education,and relevant departments need to carry out training on the sex education for young children.