Herein, Au microsnowflakes with six-fold symmetrical branches were successfully synthesized. The morphological evolution and kinetics mechanism of this microstructure were well explained. By using this micromaterial, the fabricated biosensor shows excellent electrochemical performance in the range of 1 nM to 1 mM with a low detection limit of 352 pM toward adenosine. It also provides excellent selectivity against other deoxyribonucleosides. Meanwhile, the Au microsnowflakes show good performance in surface enhanced Raman scattering for the detection of p-mercapto benzoic acid (PMBA) molecules.