Seed germination is a complex process that is regulated by various exogenous and endogenous factors, in which abscisic acid (ABA) plays a crucial role. The triphosphate tunnel metalloenzyme (TTM) superfamily exists in all living organisms, but research on its biological role is limited. Here, we reveal thatTTM2functions in ABA-mediated seed germination. Our study indicates thatTTM2expression is enhanced but repressed by ABA during seed germination. PromotedTTM2expression in35S::TTM2-FLAGrescues ABA-mediated inhibition of seed germination and early seedling development andttm2mutants exhibit lower seed germination rate and reduced cotyledon greening compared with the wild type, revealing that the repression ofTTM2expression is required for ABA-mediated inhibition of seed germination and early seedling development. Further, ABA inhibitsTTM2expression by ABA insensitive 4 (ABI4) binding ofTTM2promoter and the ABA-insensitive phenotype ofabi4-1with higherTTM2expression can be rescued by mutation ofTTM2inabi4-1 ttm2-1mutant, indicating thatTTM2acts downstream ofABI4. In addition,TTM1, a homolog ofTTM2, is not involved in ABA-mediated regulation of seed germination. In summary, our findings reveal that TTM2 acts as a downstream factor of ABI4 in ABA-mediated seed germination and early seedling growth.