Teacher work engagement is critical for work performance and child development, yet there is a limited understanding of how it is shaped from the perspective of teachers' emotion. Based on the job demand-resource model, this study tested the relationship between emotional labor strategies, teacher efficacy, grit, and work engagement. Research Findings: Through structural equation modeling, self-reports of 647 Chinese preschool teachers revealed that (1) expression of naturally felt emotions showed both a direct and an indirect (via teacher efficacy and grit) positive relationship with work engagement; (2) deep acting was associated with work engagement via promoted teacher efficacy; (3) surface acting was associated with work engagement via weakened teacher efficacy. Neither deep acting nor surface acting was linked to engagement via teacher grit. Practice or Policy: The findings call for attention to teacher emotion which is particularly important for preschool teachers in Chinese society. Guidance is needed for teachers to aptly use felt emotions to achieve classroom goals and translate the regulating process into positive beliefs about themselves.