The converter transformer is the core of the HVDC transmission project.The converter transformer is bulky and difficult to transport completely.Once the fault is repaired on-site only the on-site withstand voltage test can be carried out to ensure the safe operation after it is put into operation.This paper discusses the AC voltage withstand test and partial discharge measurement test on the field of the±1100 kV converter transformer valve side for the first time on-site.After±1100 kV Changji converter station pole I high side converter replace seat its internal insulation strength and on-site installation quality should be checked to meet the requirements of the standard regulations and product technical conditions.The valve side of the high side converter transformer AC withstand voltage and partial discharge measurement test are carried out on-site.According to the actual situation of the field by properly arranging the location of the test equipment optimizing the grounding mode wiring method simulation test and other methods to control the on-site interference level and ensure the well-off progress of the test the local discharge interference level is successfully controlled below 100 pC and the test is completed successfully.This test provides valuable experience for on-site AC withstand voltage and partial discharge testing of UHV converter transformers.