The winding arrangement is studied for the UHV converter transformer, whose line side winding connected 1 000 kV AC and rated voltage at DC side was ±1 100 kV DC. Through analyzing the advantages and disadvantages of different main insulation structure schemes, the scheme is recommended. Moreover, the electric field calculation for its main insulation structure is carried out, which shows that the recommended insulation structure arrangement is reasonable, and the insulation margin can meet the engineering requirements.