This paper discusses the effect of the 12-pulse converter input transformer configuration on the input harmonic currents. This is done because there are many transformer connection configurations, which according to the standard there are 5 transformer connection groups. The research method begins with a literature study on the 12-pulse converter. Next, determine the specifications of the 12-pulse converter and build the 12-pulse converter. Then, a theoretical analysis was carried out on the waveform of the 12-pulse converter current with the Dy11/d0 and Yd1/y0 input transformer configurations. From the analysis and simulation results, it was found that the THDi of the two 6 pulse converters obtained 29% THDi, while the 12-pulse converter inputs side obtained 11.59%-13,6% THDi. The input transformer configuration does not affect the THDi results, except for the power sent by the 12-pulse converter with the input transformer configuration Yd1_y0 to 1/3 compared to the Dy11_d0 connection.