Geopolymer cement, a sustainable alternative to conventional Portland cement, offers significant environmental benefits through reduced CO2 emissions and the utilization of industrial by-products, such as fly ash. However, a notable challenge with geopolymer cement is its tendency for strength retrogression under high curing temperatures. Thus, this study investigates the effects of incorporating silica flour into fly ash-based geopolymer cement, examining its impact on key properties including rheology, thickening time, fluid loss, and compressive strength. Ultrasonic cement analyzer (UCA) equipment was utilized to determine the compressive strength of the geopolymer cement at 3300 psi and 120 ℃ (BHST), which is the Field X’s downhole condition Findings reveal that the incorporation of 35% silica flour by weight of cement (BWOC) significantly mitigates strength degradation, enhancing both the rheological properties and thickening time while effectively reduce fluid loss. The results show that 35% silica flour by weight of cement (BWOC) mitigates the strength degradation of silica-stabilized geopolymer cement (SSGC). These enhancements highlight the pivotal role of silica flour in refining the geopolymer matrix, optimizing the cement's mechanical and durability aspects. The research accentuates silica flour’s potential in fostering the development of more robust, efficient, and eco-friendly fly ash-based geopolymer cement.