Porous geopolymer microspheres were prepared using water glass and slag as raw materials based on inverse Leidenfrost effect. The results reveal that the pore structure and pH buffering performance of the porous geopolymer microspheres can be adjusted by varying the water glass content and the water-solid ratio. When the water-solid ratio is 1.0 and the water glass content is raised from 4% to 8%， a decrease in the median pore radius， porosity， and pore specific surface area of microspheres is observed， and pH fluctuation is in the range of 1.50-1.90. When the water glass content is 4% and the water-solid ratio increases from 1.0 to 1.2， the median pore radius， porosity， and pore specific surface area of microspheres increase， and pH fluctuation exceeds 2.00. Notably， the inverse Leidenfrost effect results in the preparation of porous geopolymers with superior pH buffering performance and higher cumulative leaching amount of OH^- compared to those generated via direct gassing with hydrogen peroxide.