The Chinese National Matriculation English Test (NMET) has a test purpose of producing beneficial washback to promote senior high school English teaching and learning. This article presents a large-scale nationwide survey research on student perceptions of the NMET's before-test washback on their English learning outcomes in senior high school and the influence of the factor of home province on their views. The research participants were 20,062 first-year undergraduates from 103 universities in the Chinese mainland, and findings showed that the NMET facilitated their senior high school English learning outcomes in the surveyed skills both tested and not tested in the NMET. However, there were noticeable differences between students' expectations and realities. It was also found that home province was a significant predictor of student perceptions, though the strengths of the relationships varied. Furthermore, in order for more beneficial NMET washback, the students suggested making the NMET speaking and listening subtests mandatory across all provincial regions and administering a nationally unified NMET form. This study calls on future researchers to hold a close lens to the complexity and dynamism of the NMET washback over time and across situations.