STEM approach is an integrated approach based on co-teaching of science, technology, engineering, and mathematics. The aim of this study is to synthesize the effect of STEM approach on academic achievement and compare the effect size obtained in these studies according to the level of education (primary, secondary, high school, and university), their status of the domestic and foreign study. Meta-analysis method was used the study.In this study, 38 studies in which investigated the effect of STEM education on academic achievement between the years 2012-2018. Their effect size range between -0.107 and 10.567 In the studies examined in the study, it was determined that the effect size of the studies carried out at the primary school level is small and the studies conducted with the primary school group are mostly carried out abroad. Although it was observed that both small and large effect size was encountered in the studies at the secondary and high school level, the medium effect size was limited and university level studies have medium and large effect size. Since the number of studies carried out in our country is limited, especially in primary school level, studies in this level of education may contribute to the literature.