In this work, silica fume was used as a dispersant to treat aluminum powder foaming agent, and lightweight geopolymer-based filler materials with different dispersant contents (Ⅰ 0wt%; Ⅱ 80wt%; Ⅲ 90wt%; Ⅳ 95wt%) were prepared. The effects of foaming agent dispersion on the fluidity, setting time, compressive strength, permeability coefficient, and durability of lightweight geopolymer were investigated in depth. Moreover, the macroscopic pore structure of the sample was characterized using a stereomicroscope. The results showed that the appropriate dispersion treatment helped to improve the physical and mechanical properties of the specimens. Sample II exhibited the optimal dispersion ratio, with a 28 d compressive strength of 3.359 MPa. The high closed porosity (88.69%) effectively reduced the permeability coefficient of the specimens (1.18×10-6 cm/s), which remained at the 10-6 order of magnitude even after 14 days of immersion. In addition, the dispersion treatment of the foaming agent not only solved the pore size problem, but also optimized the pore distribution. This study not only provides a scientific basis for controllable aluminum powder foaming technology, but also offers a new strategy for the carrier materials of artificial floating islands. The research results promote the application of geopolymer-based materials in the field of artificial floating islands and are of great significance for the utilization of marine resources. This study demonstrates that waste materials can be transformed into new materials with practical value through scientific methods and innovative technologies, which not only reduces environmental pollution but also opens up a new way for the sustainable use of resources. The preparation and performance characterization of lightweight geopolymer materials for artificial floating islands reveal the possibility of geopolymer materials being applied to artificial floating island targets.