In order to solve the measurement accuracy problem caused by the temperature rise of DC voltage transformers (DCVT) resistance, this paper has been studied the heating problem for ±800 kV DCVT. The principle of resistance selection is analyzed. On this basis, the DCVT design is performed, and the heat exchange structure of DCVT is designed. Through the adoption of vortex type heat exchanger with double gas type structure is adopted to optimize the heat exchange mode and reduce the error caused by the temperature rise of resistance. To verify the design effect, a three-dimensional DCVT internal temperature rise calculation model is established considering the change of SF6 physical parameters with temperature. The calculation results show that the designed heat exchanger can reduce the internal overall temperature rise of the DCVT to 10.5%, and the axial temperature difference is reduced by 43%, and the measurement error generated by the resistance temperature rise is 0.025%, which meets the design requirements. In order to further verify the heat exchange effect, and the test of temperature rise on the voltage division ratio is carried out. Experimental results show that under the condition of temperature rise, DCVT voltage division ratio error is less than 0.2 class error limit. Both theoretical and experimental results show that the vortex heat exchange structure designed in this paper enables that the error caused by resistance temperature rise is much smaller than the required error limit, and ensures the DCVT has good measurement accuracy.