This meta-analysis explores the impact of positive instructors on learning from instructional videos. Both the contagion theory and the cognitive-affective theory of learning with media suggest that positive instructors can facilitate learning. This review analyzed 37 studies reporting various outcomes, including positive emotion, motivation, attention, cognitive load, learning experience, learning satisfaction, self-efficacy, and learning achievement. The overall findings revealed that positive instructors in instructional videos significantly enhanced learners' positive emotion, motivation, learning experience, learning satisfaction, and learning achievement, and encouraged student attention to the instructor. However, no significant effect was found regarding attention paid to visual materials, cognitive load, and self-efficacy. A series of moderating effect analyses were also conducted. The results indicated that the impact of positive instructors is influenced by instructor characteristics and emotional expressions, as well as other factors independent of the instructors. These findings provide systematic evidence and practical insights for the design of effective instructional videos.