In this work, a series of Au aerogels with exposed {110}-facets were successfully synthesized by Ostwald-ripening between two differently-sized gold nanoparticles (Au NPs). On the basis of the results of de-convoluting CV analysis and size variation of large Au NPs during their formation process, it is found that the size ratio (R) between two differently-sized Au NPs is crucial for the occurrence of surface reconstruction during the Ostwald-ripening process. Moreover, the R can be used to estimate the extent of surface reconstruction and the critical R for the occurrence of surface reconstruction in our case is about 5. Furthermore, Au6-50 aerogels with the highest ratio of {110}-facets (up to 35.5%) show excellent performance in glucose detection, and offer a short response time of 2 s, an ultrahigh sensitivity (2044.71 μA cm-2 mM-1) and the ultralow limit of detection (0.58 μM). In addition, they also exhibit good reproducibility and long-term durability. Therefore, our work provides a new way for the fabrication of Au aerogels with controlled ratios of facets by size-dependent surface reconstruction.