UHV power transmission technology is already under development and its economics. It is necessary for my country to develop UHV. One of the three key technical issues of UHV power transmission technology is UHV insulation and requirements. In order to ensure the safe and stable operation of UHV DC equipment, UHV DC test equipment must go ahead, and the stable operation of the 1200kV UHV bipolar DC generator itself as the main power supply of the test line is very important. This article first carried out the modeling and design of the bipolar high voltage DC generator, and then used the electromagnetic transient analysis program ATP-EMTP to simulate the charging process of the generator and analyze the transient state. The transient characteristics of the generator were analyzed. Influencing factors.