<p>The<i> What Is Happening In this Class</i> (WIHIC) questionnaire is most widely applied and internationally acknowledged instrument to assess classroom learning environments, but its cultural and psychometric applicability in Mainland China remains underexplored. Although a Chinese version has been translated and validated in Taiwan, linguistic and educational differences necessitate validation for Mainland Chinese high school students. This study validated a Mandarin adaptation of the WIHIC, where minor clarifications (explanatory terms in parentheses) were added to improve clarity without altering original items. Data were collected from 810 high school students (354 males, 456 females; aged 14–18, <i>M</i> = 16.41, <i>SD</i> = 0.66). The hypothesised factor structure was upheld by exploratory and confirmatory analyses. Confirmatory factor analysis showed an acceptable fit to the data (<i>χ</i>^<i>2</i> = 2770.615, <i>df</i> = 1264, <i>χ</i>^<i>2</i>/df = 2.19, SRMR = 0.069, RMSEA = 0.054, CFI = 0.90, TLI = 0.90). Validity was further confirmed through convergent and discriminant testing using average variance extracted (AVE), composite reliability (CR), and the Fornell-Larcker criterion. Measurement invariance across gender was established, supporting the scale’s equivalence for male and female students. Findings indicate that the adapted Mandarin WIHIC is robust and valid measure for examining classroom learning environments among senior high school students in Mainland China, offering researchers, educators, and policymakers a robust measure for cross-cultural and educational investigations.</p>