Sulfuric acid-methanol electrolytes were applied for the electropolishing of tantalum. The effects of electrolyte composition and voltage on the finish quality of tantalum were investigated. The optimum parameters for polishing tantalum are determined as follows: V(H2SO4):V(CH3OH) =1:7, voltage=~20 V when the stir speed is 16 m/s, and the electrolysis time is 3 min at 0 oC. The results show that RMS Rq of the polished tantalum is less than 30 nm and the requirement of tantalum surface and EOS thin film can be satisfied.