Abstract: Yuanba block in northeast Sichuan is the key area of exploration and development for Sinopec southern Marine,with the characteristics of deep reservoir buried depth,high temperature,high pressure and high containing H2S.Horizontal well drilling has difficult technical problems on measuring instrument,directional tool selection and trajectory control.Through the application of high temperature,high pressure rotary steering and high temperature screw +MWDS comparison,the directional drilling tool combination is optimized.Combined with theory and real drilling experience,the ultra deep horizontal well trajectory control technology suitable for Yuanba area has been formed,which provides technical support for marine reservoir development of Yuanba area.