The research on corona loss in high altitude area of 8×LGJ-630 conductor which is commonly used in UHV AC double circuit transmission in the same tower is studied in this paper based on the UHV corona cage built in the Ping An county(2200m), Xining City.The test conditionincludes dryness, moderate rain(6mm/h),heavy rain(12mm/h)and humidity.For the first time, the corona data of 8×LGJ-630/45 conductors in the corona cage at high altitude were obtained. Then throughfinite element method simulation calculating the electric field intensity of the corona cage wire and the actual line conductor, the corona loss of UHV AC double circuit transmission line in high altitude area is analyzed by the example of typical tower type of 1000kV UHV AC double circuit transmission line on the same tower with corona loss equivalent method. the corona data of double circuit transmission lines on the same tower at high altitude were obtained. It provides reference basis for the selection of UHV AC transmission lines in high altitude area in the future.