To address the instability and limited fire-suppression effectiveness of foam agents, a three-phase gel foam incorporating α-olefin sulfonate (AOS), alkylphenol ethoxylates (OP-10), modified bentonite, and cellulose gel was developed. The foam formula was optimized by using response surface method. Combined with Zeta potential and FTIR, the intrinsic interaction between materials was analyzed. The foam decay process, liquid discharge regularity, and viscosity change under different additives were compared. The enhancement of its fire extinguishing ability was explored. Results show that: The optimized foam achieves optimal foaming volume and half-life. Surfactant adsorption reduces the surface charge of particles and stabilizes their dispersion in liquid membrane. Cellulose is wound between particles to form a stable absorbent skeleton and delay decay of foam. Foam adheres stably to solids and covers them with barrier, inhibiting wood burning. The time to extinguish wood stack fire was 84 s, a 36.84% improvement over Class A foam extinguishing agents.