AbstractStyrene-acrylic organic emulsion was synthesized, prepared, modified by silane coupling agents, and added to metakaolin-based geopolymer. Combining mechanical properties, x-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and energy-dispersive x-ray spectroscopy/scanning electron microscopy (SEM-EDS), the effect of organic emulsion on the properties of geopolymer was analyzed. Results show that the flexural strength of the organic-inorganic hybrid geopolymer formed after adding the modified emulsion was significantly improved. Adding an appropriate amount of organically modified emulsion can improve the mechanical properties of geopolymer cured for 3 days. When adding 0.5 wt% modified emulsion (A-151), the 28-day flexural strength of the hybrid geopolymer reached its maximum value, which was 25.81% higher than that of pure metakaolin-based geopolymer. After the emulsion was added, the compressive strength of geopolymer samples decreased slightly, which may be related to the increased moisture brought by the emulsion and the viscosity of the emulsion. The increased flexural-to-compressive-strength ratio of samples indicate that the toughness of the geopolymer was improved. It was found using SEM-EDS that the organic phase has good compatibility with the inorganic matrix, and the organic phase participates in the polymerization of geopolymer.