Abstract: A kind of high temperature resistible emulsifying agent is successfully used to improve the temperature resistance of water-in-oil drilling fluid, from 180℃~220℃. The modified drilling fluid is used in the 4590~5000m interval of Pushen-1, and it shows its advantages over the high temperature stability, suspension, and cutting transportation and filtrate control abilities. During the 160 days of drilling and logging in high temperature environment, more than 50 trips and instruments running were smoothly conducted. The drilling fluid is a good alternative in drilling the high temperature deep wells in Songliao Basin.