The purpose of this study aimed to explore the relationship of elementary school science and technology teachers' knowledge management and teaching effectiveness in Changhua. This study employed questionnaire survey: Totally 239 questionnaires had been were randomly selected as stratified samples, and 221 of them are effective. All samples were analyzed through the ways of One-way ANOVA and Regression Analysis. The major findings were drawn from this study: (1) Elementary school teachers in the field of science and technology in Changhua had mean to high level of perception toward knowledge management and teaching effectiveness; (2) Elementary school teachers in the field of science and technology in Changhua showed partial significant difference in the perception of knowledge management and teaching effectiveness, including different backgrounds in education level and current job position; (3)The variable “knowledge management” could be used as the best prediction for “ teaching effectiveness” of elementary school science and technology teachers in Changhua, especially in ”knowledge application” facet. According to the findings and conclusions given above, the study proposed recommendations for educational authorities, school teachers and administrators, and future researches.