Corona loss is the important factor in the conductor selection criteria for 1 000 kV UHVAC transmission line. In this paper, the popular corona loss estimation theory is discussed. Based on a practical project, the corona loss is calculated using Bonnevile Power Administration (BPA)model, in which the weather condition is considered. The relationship between corona loss and resistance loss is compared thereafter. The research results could be referenced for future designation on the type of UHVAC transmission line.