Teacher-student interactions (TSIs) are crucial in shaping student learning attitudes and outcomes. Current literature primarily focuses on within-subject TSI effects, neglecting potential cross-subject TSI effects and related gender disparities. Using data from Chinese adolescents and extending the dimensional comparison theory, this study examines the within- and cross-subject effects of TSI on math-related attitudes and outcomes with a focus on gendered patterns. We find significant gender disparities: All else equal, boys interact more with both math and non-math teachers than girls in Chinese classrooms. Higher levels of math TSIs are associated with increased math self-efficacy, motivation, and subsequent academic performance and STEM aspirations. Moreover, positive math TSIs help girls challenge gender-math stereotypes while reinforcing them for boys. We also identify a cross-subject contrast effect: Positive non-math TSIs have an unintended consequence of reinforcing the gender-math stereotype for girls but challenging them for boys. We discuss the theoretical and empirical implications.