Carbon aerogels are special porous materials with low density and large specific surface area and have advanced applications. As a new type of carbon nanomaterials, graphdiynes (GDY) aerogel possess a highly π-conjugated structure, unique sp/sp2-hybridized linkages, and well-distributed intrinsic pores, which endow GDY aerogel with great potential applications. However, the fabrication of macroscopic GDY aerogel is still an ongoing challenge due to intrinsic synthetic difficulties. Here, a modified Hiyama coupling reaction was developed to synthesize GDY aerogel via in-situ deprotection of trimethylsilane groups and subsequent freeze-drying. The synthesized GDY aerogel has a low density of ∼12 mg cm-3, a high specific surface area of ∼909 m2 g-1, and a porosity of ∼98%, which is superior to other GDY nanomaterials. The adsorption capacity of GDY aerogel toward H2, CO2, and CH4 is investigated, and competitive adsorption abilities are obtained.