The invention relates to a preparation method of an aerogel composite adsorbent for efficient removal of indoor formaldehyde. The method specifically includes the steps of: adding graphite oxide into an aqueous solution, and conducting uniform ultrasonic dispersion to obtain an graphene oxide aqueous solution; adding graphene carbon nanodots into the prepared graphene oxide aqueous solution, conducting uniform ultrasonic dispersion, then adding a reducing agent and ammonia water in order, and stirring the mixture fully to obtain a mixed solution; soaking a sponge into the mixed solution, performing sealing, then placing the product in constant temperature water bath to carry out water bath reaction; at the end of the water bath reaction, removing redundant solution, and carrying out freeze drying so as to obtain the adsorbent. Compared with the prior art, the preparation method provided by the invention is simple, mild, green and environment-friendly, and has no secondary pollution, the raw materials are easily available, and the prepared aerogel composite material has significantly improved formaldehyde adsorption performance uo to 22.81mg / g, and the longest penetration time is 7500min / g. Thus, the aerogel composite adsorbent has good application prospects.