Tuff powder (TP) has attracted significant attention due to its abundant resources, low carbon emissions, and potential enhancements in concrete property. This study investigates the effect of TP on the mechanical properties, hydration behavior, pore structure, microstructure morphology, economic and environmental analysis of moderate-heat portland cement (MHPC), comparing it with MHPC-based materials containing fly ash (FA). The synergistic morphological effect and micro-aggregate filling action of FA and TP result in higher early strength in the fly ash-tuff powder (FT) group mortar. The CH content and chemically bounded water content of TP paste are higher, showing a better early hydration promotion effect. The pore structure of the composite cement mortar is changed due to the addition of the admixture. Furthermore, the multi-factor response strength and strength activity index (SAI) model were developed based on response surface methodology (RSM), linking to TP specific surface area, dosage, and specimen curing age. This provides a reference for more accurate and comprehensive prediction of cement mortar property, quantification of effects, optimization of mix proportions, and evaluation methods for the activity of pozzolanic materials.