The purpose of this study is to verify the validity of the revised STMI, which is a revised and supplemented version of the Systems Thinking Measuring Instrument (STMI) developed by Lee et al. (2013) for high school students. For this purpose, we used data from 475 high school students’ responses to 20 Revised STMI questions and 20 STS scale questions. Validity verification includes item response analysis (Item Reliability, Item Map, Infit and Outfit MNSQ, and DIF of male and female groups), exploratory factor analysis (main axis factor analysis using Promax), and confirmatory factor analysis using structural equation model. And central/cross validity verification and correlation analysis between the two scales were used. The research results are as follows. First, as a result of the item response analysis of the Revised STMI 20 questions, Item Reliability was .98 and Infit MNSQ was .84~1.39, and valid results were also analyzed in Item Map and DIF analysis. Second, in the exploratory factor analysis, all sub-questions of the five sub-factors showed factor loading values of .3 or higher, and the reliability of each factor was .631~.800 and the overall reliability was .863. Third, in the confirmatory factor analysis, all model fit values were good (χ2/df: 2.406, CFI: .923, TLI: .908, SRMR: .046, RMSEA: .054), and the convergent validity and crossvalidity were also established. The results showed that the model was suitable. Lastly, in the correlation analysis with the 20 items of the STS scale, the correlation between all items was .754, and the correlation with STS items for each sub-factor was high, ranging from .426 to .658. Therefore, in the case of the Revised STMI, significant results were obtained not only in construct validity but also in official validity, and the results of this study showed improved validity results compared to research results using existing scales. Continuously, additional validation research should be conducted so that the Revised STMI can be applied to various groups, including not only high school students, but also elementary and middle school students, and college students. In addition, ongoing research on the relationship between system thinking and other learning-related measures should be actively conducted using validated instrument.