The purpose of this study is to explore the mediating effect of school climate perception on the relation between achievement motivation (including SOAM and IOAM) and academic performance. 324 valid questionnaires from middle school students were used to analyze. Correlation analysis results show that there is a significant negative correlation between academic performance and SOAM, but academic performance positively correlated with IOAM. Furthermore, the perception of study pressure, school order and discipline are negatively correlated with academic performance, while the perception of teacher-student relationship, classmate relationship and the development of diversity are positively correlated with academic performance. Mediation analysis show that there is a partial mediating effect of the study pressure perception on the relationship between SOAM, IOAM and academic performance. Findings from this study suggest that school education should guide students to clarify their learning goals and reduce external study pressure, which helps to promote their academic performance.