SiO2 aerogel was used to modify geopolymers. Influence of different slag and aerogel content on the compressive strength, dimensional stability, water loss and microstructure were analyzed to provide guidance for solving the problem of geopolymer drying shrinkage. Results show that strength of specimens with low slag content at 28 days is greatly increased. When slag content is 30%, dimensional stability is significantly enhanced as the increase of aerogel content. With the increase of age, water loss of specimens within 7 days is much greater than the specimens after 7 days. As the aerogel content increases, water loss of specimens with low slag content is first reduced and then increased. However, water loss of specimens with high slag content increases first and then decreases. When slag content is 30% and aerogel content is 8%, the microstructure of specimens is the most compact.