Humility is a traditionally esteemed virtue in Chinese culture and a desired personal quality in teachers. While previous research shows that teacher humility has a positive effect on students, there is limited empirical research on how it impacts student learning motivation. Therefore, we designed a moderated mediation model to examine how teacher humility affects college students' learning motivation, focusing on the mediating role of academic self-efficacy and the moderating role of teacher ability trustworthiness. We used a questionnaire to survey 808 college students from the Zhejiang, Guangdong, and Henan provinces in China and utilized SPSS 19.0 and SPSS macro PROCESS for hypothesis testing. The findings suggest that teacher humility indirectly and positively influences student learning motivation by enhancing academic self-efficacy. Moreover, teacher ability trustworthiness moderates the relationship between teacher humility and academic self-efficacy, as well as the indirect effect of teacher humility on student learning motivation via academic self-efficacy. There was a more significant positive correlation between teacher humility and academic self-efficacy for students with higher than lower trust in their teachers' abilities. Based on these outcomes, we recommend that teachers exhibit humility in their interactions with students to increase learning motivation. Teachers should also enhance their professional abilities to win students' trust. This study also discusses limitations and directions for future research.