In deep drilling， with the increasing of borehole depth， drilling conditions become more complicated， drilling rate decreases， borehole quality can not be guaranteed， and controlling the borehole direction is difficult. In Russia， the Rotary Steerable System-RSS is used actively with the deflection function of the downhole bit to achieve build-up， drop and hold of inclination. The accuracy of the system is very high（±0.1°）， the depth of the borehole can reach 13 km with the the drilling length per run up to 1000m. The system can provide reference for deep drilling， particularly for ultra deep geological drilling in China.