Abstract: We review the search for new physics phenomena beyond the Standard Model through rare processes at the Beijing Spectrometer Ⅲ (BESⅢ). Utilizing the huge data samples of charmonium states such as J/ψ, ψ(3686), and ψ(3770), the BESⅢ collaboration hunts for rare processes such as weak decays of charmonium, flavor-changing neutral currents, charged lepton flavor violation, as well as violations of baryon number, lepton number, C parity, and CP parity. We also search for dark matter and invisible decays, as well as the exotic light states beyond the Standard Model. These studies offer unique opportunities to explore new physics beyond the Standard Model in the tau-charm energy region.