The study presents the design and development of a rice straw-based mushroom growing substrate pasteurizing and cooling system aimed at improving mushroom production efficiency by utilizing agricultural waste. Key findings include established operating times and temperature ranges for pasteurization and cooling processes, along with recorded rates for pasteurization, cooling, and substrate discharging. This process is positioned to enhance the viability of mushroom cultivation for small-scale farmers in the Philippines, promoting better use of rice straw and addressing agricultural waste issues.