Evaluation is an important tool for facilitating and promoting the growth of school members and improving the quality of schooling. The Organisation for Economic Co-operation and Development (OECD) claimed that effective school evaluation involves continuously using the results of such evaluations in school operations (2019). Based on the evaluation process, each school organisation develops a certain evaluation culture through acts of self-reflection and learning. Therefore, the purpose of this study is threefold. First, it focuses on 'constructing indicators of the high school evaluation culture'; second, it emphasises 'verifying the indicators of the high school evaluation culture'; and third, it involves 'testing the structural relationship model of the impact of the high school evaluation culture on school effectiveness'. A total of approximately 40 scholars working in the field of educational evaluation, educational administrators, administrators and teachers were recruited for this study to consult on the construction of indicators of the high school evaluation culture and to complete a questionnaire regarding fuzzy ethics; these participants were drawn from 372 schools in Taiwan. Educators working at public and private high schools completed a questionnaire survey. Finally, a measurement model for the construction of indicators of the high school evaluation culture was tested using a linear structural equation model to examine the reliability and validity of the indicators (i.e. questionnaires). The final results of this study are as follows: (1) School: The evaluation culture index includes five levels and 34 indicators, which exhibit good reliability and validity. (2) The verification of the evaluation culture and the school performance structure model indicate a good degree of adaptation. (3) School performance can be improved through a high-quality evaluation culture, which has a direct impact in this context. Then, based on the findings of this study, relevant suggestions are proposed for schools, principals, educational personnel, and researchers.