Topological insulators (TIs) are new kind of electronic materials with special energy band structures and topological properties. With topologically-protected metallic surface state and insulating bulk state, TIs have excellent electronic and optical characteristics containing the excitation of surface plasmons. Herein, we deposited the antimony telluride (Sb2Te3) TI layer using the magnetron sputtering method and employed focused ion beam (FIB) lithography to fabricate a nanocolumn array on the Sb2Te3 layer. The experimental measurements show that the localized surface plasmon resonances (LSPRs) can be excited in the Sb2Te3 TI nanocolumn array in the visible region. The resonance wavelength is dependent on the size and period of the Sb2Te3 nanocolumn array. The experiment results are in good agreement with the finite-difference time-domain (FDTD) numerical simulations. Moreover, the LSPR enables to realize the microscale optical sensing of the surrounding refractive index with a high sensitivity of 450 nm/RIU. This work will pave a new pathway for the excitation of surface plasmons in TI materials and their applications in optical sensing at the microscale.